![ERRATA[1]
Vol. II
Page xviii, line 7, for Ophicæphalus read Ophicephalus
xviii, " 37, for Mononactylus read Monodactylus
xix, " 33, for Trachicephales read
Trachicephalus
xx, " 37, for Regaleaus glesneacsanius read
Regalecus russelli
xxi, " 2, for Etopus read Etropus
xxi, " 35, for Zoacres read Zoarces
1, " 7, for jaws read jaw
14, " 9, for hetercoercal read heterocercal
136, " 3, for Evermannellus read Evermannella
170, " 11, for the fin read the dorsal fin
171, " 10, for have read has
303, legend, for Lacepède read Lacépède
307, line 14, for vertebrate read vertebral
311, " 12, not clearly stated. The air-bladder is
least developed in those species
which cling closest to the bottom
of the stream
350, legend, for Apomotes read Apomotis
355, line 18, for ours read our
357, " 14, for chætodon read Chætodon
358, " 17, for Scriænidæ read Sciænidæ](https://image.slidesharecdn.com/54488-250618112215-ff629cbc/85/Data-Analysis-with-Microsoft-Power-Bi-Brian-Larson-37-320.jpg)
![Ganoids, the first by Francis M. Balfour and William Kitchen Parker,
the second from the pen of Theodore Gill.
Balfour and Parker ("Structure and Development of Lepidosteus," pp.
430-433) thus discuss the
Systematic Position of Lepidosteus.—"Alexander Agassiz
concludes his memoir on the development of Lepidosteus by
pointing out that in spite of certain affinities in other directions this
form is 'not so far removed from the bony fishes as has been
supposed.' Our own observations go far to confirm Agassiz's opinion.
"Apart from the complete segmentation, the general development of
Lepidosteus is strikingly Teleostean. In addition to the general
Teleostean features of the embryo and larva, which can only be
appreciated by those who have had an opportunity of practically
working at the subject, we may point to the following developmental
features[2]
as indicative of Teleostean affinities:
"(1) The formation of the nervous system as a solid keel of the
epiblast.
"(2) The division of the epiblast into a nervous and epidermic
stratum.
"(3) The mode of development of the gut.
"(4) The mode of development of the pronephros; though the
pronephros of Lepidosteus has primitive characters not retained by
Teleostei.
"(5) The early stages in the development of the vertebral column.
2. The features enumerated above are not in all cases confined to Lepidosteus
and Teleostei, but are always eminently characteristic of the latter.
"In addition to these, so to speak, purely embryonic characters there
are not a few important adult characters:
"(1) The continuity of the oviducts with the genital glands.
"(2) The small size of the pancreas, and the presence of numerous
so-called pancreatic cæca.](https://image.slidesharecdn.com/54488-250618112215-ff629cbc/85/Data-Analysis-with-Microsoft-Power-Bi-Brian-Larson-44-320.jpg)
!["To the distinctive set of characters given by Müller we may probably
add the following:
"(1) Oviducts and urinary ducts always unite, and open by a
common urogenital aperture behind the anus.
"(2) Skull hyostylic.
"(3) Segmentation complete in the types so far investigated, though
perhaps Amia may be found to resemble the Teleostei in this
particular.
"(4) A pronephros of the Teleostean type present in the larva.
"(5) Thalamencephalon very large and well developed.
"(6) The ventricle in the posterior part of the cerebrum is not divided
behind into lateral halves, the roof of the undivided part being
extremely thin.
"(7) Abdominal pores always present.
"The great number of characters just given are amply sufficient to
differentiate the Ganoids as a group; but, curiously enough, the only
characters, amongst the whole series which have been given, which
can be regarded as peculiar to the Ganoids are (1) the characters of
the brain, and (2) the fact of the oviducts and kidney-ducts uniting
together and opening by a common pore to the exterior.
"This absence of characters peculiar to the Ganoids is an indication
of how widely separated in organization are the different members
of this great group.
"At the same time, the only group with which existing Ganoids have
close affinities is the Teleostei. The points they have in common with
the Elasmobranchii are merely such as are due to the fact that both
retain numerous primitive vertebrate characters,[3]
and the gulf
which really separates them is very wide.
3. As instances of this we may cite (1) the spiral valve; (2) the frequent
presence of a spiracle; (3) the frequent presence of a communication
between the pericardium and the body-cavity; (4) the heterocercal tail.](https://image.slidesharecdn.com/54488-250618112215-ff629cbc/85/Data-Analysis-with-Microsoft-Power-Bi-Brian-Larson-47-320.jpg)
!["There is again no indication of any close affinity between the
Dipnoans and, at any rate, existing Ganoids.
"Like the Ganoids, the Dipnoans are no doubt remnants of a very
primitive stock; but in the conversion of the air-bladder into a true
lung, the highly specialized character of their limbs,[4]
their peculiar
autostylic skulls, the fact of their ventral nasal openings leading
directly into the mouth, their multi-segmented bars (interspinous
bars) directly prolonged from the neural and hæmal and supporting
the fin-rays of the unpaired dorsal and ventral fins, and their well-
developed cerebral hemispheres, very unlike those of Ganoids and
approaching the Amphibian type, they form a very well-defined
group and one very distinctly separated from the Ganoids.
4. Vide F. M. Balfour, "On the Development of the Skeleton of the Paired Fins of
Elasmobranchs," Proc. Zool. Soc., 1881.
"No doubt the Chondrostean Ganoids are nearly as far removed from
the Teleostei as from the Dipnoans, but the links uniting these
Ganoids with the Teleostei have been so fully preserved in the
existing fauna of the globe that the two groups almost run into each
other. If, in fact, we were anxious to make any radical change in the
ordinary classification of fishes, it would be by uniting the Teleostei
and Ganoids, or rather constituting the Teleostei into one of the
subgroups of the Ganoids, equivalent to the Chondrostei. We do not
recommend such an arrangement, which in view of the great
preponderance of the Teleostei amongst living fishes would be highly
inconvenient, but the step from Amia to the Teleostei is certainly not
so great as that from the Chondrostei to Amia, and is undoubtedly
less than that from the Selachii to the Holocephali."
Gill on the Ganoids as a Natural Group.—Dr. Gill observes
("Families of Fishes," 1872): "The name Ganoides (or Ganiolepedoti)
was originally framed by Prof. Agassiz as an ordinal term for fishes
having the scales (when present) angular and covered with enamel;
and in the group so characterized were combined the Ganoids of
subsequent authors as well as the Teleostean orders Plectognathi,
Lophobranchii, and Nematognathi, and (subsequently) the genus](https://image.slidesharecdn.com/54488-250618112215-ff629cbc/85/Data-Analysis-with-Microsoft-Power-Bi-Brian-Larson-48-320.jpg)
![are imperfectly ossified; caudal fin mostly heterocercal, the scales
mostly rhombic in form. All the members of this group are now
extinct.
The Palæoniscidæ.—The numerous genera of this order are
referred to three families, the Palæoniscidæ, Platysomidæ, and
Dictyopygidæ; a fourth family, Dorypteridæ, of uncertain relations,
being also tentatively recognized. The family of Palæoniscidæ is the
most primitive, ranging from the Devonian to the Lias, and some of
them seem to have entered fresh waters in the time of the coal-
measures. These fishes have the body elongate and provided with
one short dorsal fin. The tail is heterocercal and the body covered
with rhombic plates. Fulcra or rudimentary spine-like scales are
developed on the upper edge of the caudal fin in most recent
Ganoids, and often the back has a median row of undeveloped
scales. A multitude of species and genera are recorded. A typical
form is the genus Palæoniscum,[5]
with many species represented in
the rocks of various parts of the world. The longest known species is
Palæoniscum frieslebenense from the Permian of Germany and
England. Palæoniscum magnum, sixteen inches long, occurs in the
Permian of Germany. From Canobius, the most primitive genus, to
Coccolepis, the most modern, is a continuous series, the
suspensorium of the lower jaw becoming more oblique, the basal
bones of the dorsal fewer, the dorsal extending farther forward, and
the scales more completely imbricate. Other prominent genera are
Amblypterus, Eurylepis, Cheirolepis, Rhadinichthys, Pygopterus,
Elonichthys, Ærolepis, Gyrolepis, Myriolepis, Oxygnathus,
Centrolepis, and Holurus.
5. This word is usually written Palæoniscus, but Blainville, its author (1818),
chose the neuter form.](https://image.slidesharecdn.com/54488-250618112215-ff629cbc/85/Data-Analysis-with-Microsoft-Power-Bi-Brian-Larson-54-320.jpg)
Data Analysis with Microsoft Power Bi Brian Larson
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- 6. Contents 1. Cover 2. Title Page 3. Copyright Page 4. Dedication 5. Contents at a Glance 6. Contents 7. Acknowledgments 8. Part I Understanding Business Intelligence and Power BI 1. Chapter 1 How to Use This Book 1. The Tool Chest Called Power BI 1. The BI Process 2. Power BI Parts and Pieces 2. The Right Tool(s) for the Job 1. Consuming Power BI Reports 2. Power BI as a Data Visualization Tool 3. Power BI as a Modeling Tool 4. Power BI as a Data Warehouse/Data Mart 3. Where to Find What You Need 1. Obtaining Power BI Desktop Software 2. Sample Code and Supporting Materials 3. Information on Power BI New Features and Enhancements 4. How to Succeed at Self-Service Analytics
- 7. 2. Chapter 2 Successful Self-Service Analytics 1. What Is Business Intelligence? 1. Defining KPIs 2. Is Your Organization Ready for BI? 1. Desire 2. Realistic Expectations 3. Ongoing Care and Feeding 4. Well-Defined KPIs 5. Actionable KPIs 6. Reliable Sources of Data 3. Implementation: Best Practices 1. Take an Iterative Implementation Approach 2. Utilize a Data Warehouse/Data Mart 3. Cleanse and Validate During Data Gathering 4. Create User-Friendly Data Models 5. Publish Latency 6. Provide Training and Support 7. Use the Right Tool for the Job 8. Establish Standards and Limits 4. Successfully Using Power BI 9. Part II Interacting with Power BI 1. Chapter 3 Power BI Architecture 1. The Power BI Architecture 1. Power BI Desktop 2. The Power BI Service 3. The Power BI Report Server 4. The Power BI Mobile App
- 8. 2. Power BI Desktop Optimizations 3. Power BI Updates 4. Microsoft On-premises Data Gateway 5. What Does the Data Have to Say? 2. Chapter 4 Using Power BI Visualizations 1. Power BI Desktop 1. Obtaining What You Need 2. Opening the Report/Preparing the Environment 2. Interacting with a Power BI Report 1. Working with a Single Report Item 2. Interacting with Multiple Report Items 3. Changing the Data with Slicers and Filters 1. Slicers 2. Filters 4. Navigating Power BI Reports 1. Drill Down and Drillthrough 2. Buttons 3. Bookmarks 4. Additional Data Interactions 5. A Cloudy Forecast 3. Chapter 5 Using the Power BI Service (PowerBI.com) 1. PowerBI.com 1. The Organization of PowerBI.com 2. Connecting to PowerBI.com 3. The Navigation Pane
- 9. 2. Workspaces 1. Reports 2. Dashboards 3. Workbooks 4. Datasets 5. Dataflows 3. Additional Areas and Items Within PowerBI.com 1. Additional Navigation Pane Items 2. Additional Buttons 4. How It All Gets Made 10. Part III Creating Visualizations 1. Chapter 6 Basic Data Visualizations 1. Learn By Doing 1. Starting Point 2. Basic Visualizations 1. Maximum Miniatures Manufacturing 2. Our First Report Page 3. Text-based Visualizations 4. Graphical Visualizations 3. Interactivity 1. Slicers 2. Filters 3. Drillthrough 4. Geographic Visualizations
- 10. 1. Bing Map Visualizations 2. Shape Map Visualizations 3. GIS Map Visualizations 5. Other Visual Elements 1. Text Boxes, Images, and Shapes 6. Fancy Formatting 2. Chapter 7 Visualization Formatting 1. The Visualization Format Tab 1. Report Page 2. All Items 3. Charts 4. Additional Chart Functional Groups 5. Table and Matrix 6. Card and Multi-row Card 7. Pie Chart, Donut Chart, Treemap, and Maps 8. Funnel 9. Gauge 10. KPI 11. Slicer 12. Button, Shape, and Image 2. Advanced Formatting Dialog Boxes 1. Conditional Formatting Advanced Controls Dialog Box 2. Data Bars Advanced Controls Dialog Box 3. The Visualization Analytics Tab 1. Types of Analytics Lines 2. Controls for Editing Analytics Lines
- 11. 4. Themes 5. New Ways to Interact and Visualize 3. Chapter 8 Advanced Interactivity and Custom Visualizations 1. Controlling Interactivity 1. Controlling Interactions 2. Synchronizing Slicers 2. Creating Interactivity 1. Custom Tooltips 2. Bookmarks 3. Selection Pane 4. Buttons 3. Customizing Visualizations 1. Custom Visualizations from the Marketplace 2. Custom Visualizations from R and Python 3. Creating a Custom Shape Map 4. Moving on to Modeling 11. Part IV Building Data Models 1. Chapter 9 Loading Data with Power BI 1. Gathering Data 1. Get Data 2. Power BI Connection Types 2. Transforming Data During the Data Import 1. The Power BI Query Editor 2. A New Sample: World Population
- 12. 3. Repeating and Changing the Data Import 1. Refreshing Data in Power BI Desktop 2. Modifying Queries 3. The Advanced Editor and the Power Query Formula Language 4. Data Source Permissions 4. Relationships and Intermediate Tables 1. Creating an Intermediate Table from a Data Source 2. Manually Creating Intermediate Tables 5. Parameters 1. Putting Parameters to Use 6. Transformers 2. Chapter 10 Power BI Transformation Reference 1. Transformation Reference 1. Informational-Only Transformations 2. Transformations on the Query Editor Home Tab 3. Transformations on the Query Editor Transform Tab 4. Transformations on the Query Editor Add Column Tab 2. Model Building 3. Chapter 11 Creating a Tabular Model in Power BI 1. Relationships
- 13. 1. Creating Relationships 2. User-Friendly Models 1. Hiding Columns from the End User 2. Column Names and Descriptions 3. Formatting and Categories 1. One Final Relationship 2. Data Categories 3. Hierarchies, Groups, and Bins 4. Measuring Up 4. Chapter 12 Measures and Calculated Columns 1. Calculated Columns 1. Creating a Calculated Column 2. The Context for Calculated Columns 2. Measures 1. Default Summarization 2. Explicit Measures 3. Measures and Context 4. Defining Context Within a Measure 5. Time Analytics 6. Row-by-Row Calculations 7. The FILTER() Function 3. DAX Variables 1. Declaring DAX Variables and Assigning a Value 2. Using a DAX Variable 3. Using Return in a Measure
- 14. 4. Everything DAX 5. Chapter 13 DAX Language Reference 1. DAX Operators 1. Comparison Operators 2. Arithmetic Operators 3. Text Operator 4. Logical Operators 2. DAX Functions 1. Modifying Context 2. Table-Valued Functions 3. Aggregate Functions 4. DAX Functions for Time Analytics 5. Parent/Child Relationships 6. Additional DAX Functions 3. Additional Modeling 6. Chapter 14 Additional Power BI Desktop Features 1. Additional Power BI Data Model Features 1. Synonyms 2. Linguistic Schemas 3. Display Folder 4. What-If Parameters 5. Roles 2. Performance Analyzer 1. Capturing Performance Information 2. Viewing the DAX Query 3. Import and Export
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- 16. 1. Excel Workbook Content 2. Power BI Templates 4. Spreading the Word 12. Part V Sharing Content 1. Chapter 15 Sharing Content on the Power BI Service (PowerBI.com) 1. The Power BI Service and Data Refresh 1. The On-premises Data Gateway 2. The On-premises Data Gateway Architecture 3. Installing the On-premises Data Gateway 4. Managing the On-premises Data Gateway 5. Managing the On-premises Data Gateway (personal mode) 6. Setting a Dataset for Scheduled Refresh 2. The Power BI Service and Sharing 1. Using Share 2. Using Content Packs 3. Using Apps 3. The Power BI Service and Row-Level Security 1. Assigning Users to a Custom Security Role 4. Another Way to Share 2. Chapter 16 Saving to the Power BI Report Server 1. Power BI Service and Power BI Report Server Comparison 1. Versions
- 17. 2. Power BI Desktop Optimizations 2. Installing Power BI Report Server 1. The Power BI Report Server Installation Executable 2. The Report Server Configuration Manager 3. The Report Catalog 1. Folders 2. The Web Portal 3. Saving a Report to the Power BI Report Server 4. Security 1. Folder and Report Security 2. Row-Level Security 5. Branding the Power BI Report Server 1. Modifying the Site Name 2. Creating a Brand Package 6. Powered Up and Ready to Go 13. Index Guide 1. Cover 2. Title Page 3. Data Analysis with Microsoft Power BI
- 18. Page List 1. i 2. ii 3. iii 4. iv 5. v 6. vi 7. vii 8. viii 9. ix 10. x 11. xi 12. xii 13. xiii 14. xiv 15. xv 16. xvi 17. 1 18. 2 19. 3 20. 4 21. 5 22. 6 23. 7 24. 8 25. 9 26. 10 27. 11 28. 12 29. 13 30. 14 31. 15 32. 16 33. 17 34. 18 35. 19 36. 20 37. 21
- 19. 38. 22 39. 23 40. 24 41. 25 42. 26 43. 27 44. 28 45. 29 46. 30 47. 31 48. 32 49. 33 50. 34 51. 35 52. 36 53. 37 54. 38 55. 39 56. 40 57. 41 58. 42 59. 43 60. 44 61. 45 62. 46 63. 47 64. 48 65. 49 66. 50 67. 51 68. 52 69. 53 70. 54 71. 55 72. 56 73. 57 74. 58 75. 59 76. 60 77. 61
- 20. 78. 62 79. 63 80. 64 81. 65 82. 66 83. 67 84. 68 85. 69 86. 70 87. 71 88. 72 89. 73 90. 74 91. 75 92. 76 93. 77 94. 78 95. 79 96. 80 97. 81 98. 82 99. 83 100. 84 101. 85 102. 86 103. 87 104. 88 105. 89 106. 90 107. 91 108. 92 109. 93 110. 94 111. 95 112. 96 113. 97 114. 98 115. 99 116. 100 117. 101
- 21. 118. 102 119. 103 120. 104 121. 105 122. 106 123. 107 124. 108 125. 109 126. 110 127. 111 128. 112 129. 113 130. 114 131. 115 132. 116 133. 117 134. 118 135. 119 136. 120 137. 121 138. 122 139. 123 140. 124 141. 125 142. 126 143. 127 144. 128 145. 129 146. 130 147. 131 148. 132 149. 133 150. 134 151. 135 152. 136 153. 137 154. 138 155. 139 156. 140 157. 141
- 22. 158. 142 159. 143 160. 144 161. 145 162. 146 163. 147 164. 148 165. 149 166. 150 167. 151 168. 152 169. 153 170. 154 171. 155 172. 156 173. 157 174. 158 175. 159 176. 160 177. 161 178. 162 179. 163 180. 164 181. 165 182. 166 183. 167 184. 168 185. 169 186. 170 187. 171 188. 172 189. 173 190. 174 191. 175 192. 176 193. 177 194. 178 195. 179 196. 180 197. 181
- 23. 198. 182 199. 183 200. 184 201. 185 202. 186 203. 187 204. 188 205. 189 206. 190 207. 191 208. 192 209. 193 210. 194 211. 195 212. 196 213. 197 214. 198 215. 199 216. 200 217. 201 218. 202 219. 203 220. 204 221. 205 222. 206 223. 207 224. 208 225. 209 226. 210 227. 211 228. 212 229. 213 230. 214 231. 215 232. 216 233. 217 234. 218 235. 219 236. 220 237. 221
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- 27. Exploring the Variety of Random Documents with Different Content
- 28. Morone americana, White Perch 322 Promicrops itaiara, Florida Jewfish 323 Epinephelus striatus, Nassau Grouper: Cherna criolla 324 Epinephelus drummond-hayi, John Paw or Speckled Hind 325 Epinephelus morio, Red Grouper 325 Epinephelus adscensionis, Red Hind 326 Mycteroperca venenosa, Yellow-fin Grouper 327 Hypoplectrus unicolor nigricans 328 Epinephelus niveatus, Snowy Grouper 329 Rypticus bistrispinus, Soapfish 330 Lobotes surinamensis, Flasher 331 Priacanthus arenatus, Catalufa 331 Pseudopriacanthus altus, Bigeye 332 Lutianus griseus, Gray Snapper 334 Lutianus apodus, Schoolmaster 335 Hoplopagrus guntheri 336 Lutianus synagris, Lane Snapper or Biajaiba 336 Ocyurus chrysurus, Yellow-tail Snapper 337 Etelis oculatus, Cachucho 337 Xenocys jessiæ 338 Aphareus furcatus 339 Hæmulon plumieri, Grunt 340 Anisotremus virginicus, Porkfish 341 Pagrus major, Red Tai of Japan 342 Ebisu, the Fish-god of Japan, bearing a Red Tai 343 Stenotomus chrysops, Scup 344 Calamus bajonado, Jolt-head Porgy 345 Calamus proridens, Little-head Porgy 345 Diplodus holbrooki 346 Archosargus unimaculatus, Salema, Striped Sheepshead 347
- 29. Xystæma cinereum, Mojarra 348 Gerres olisthostomus, Irish Pampano 349 Kyphosus sectatrix, Chopa or Rudder-fish 349 Apomotis cyanellus, Blue-green Sunfish 350 Pseudupeneus maculatus, Red Goatfish or Salmonete 351 Mullus auratus, Golden Surmullet 352 Cynoscion nebulosus, Spotted Weakfish 353 Bairdiella chrysura, Mademoiselle 355 Sciænops ocellata, Red Drum 356 Umbrina sinaloæ, Yellow-fin Roncador 357 Menticirrhus americanus, Kingfish 357 Pogonias chromis, Drum 358 Gnathypops evermanni 359 Opisthognathus macrognathus, Jawfish 359 Opisthognathus nigromarginatus 360 Chiasmodon niger, Black Swallower 360 Cirrhitus rivulatus 364 Trichodon trichodon, Sandfish 364 Anabas scandens, Climbing Perch 366 Channa formosana 371 Ophicephalus barca, Snake-headed China-fish 371 Cymatogaster aggregatus, White Surf-fish 372 Hysterocarpus traski, Fresh-water Viviparous Perch 373 Hypsurus caryi 373 Damalichthys argyrosomus, White Surf-fish 374 Rhacochilus toxotes, Thick-lipped Surf-fish 374 Hypocritichthys analis, Silver Surf-fish, Viviparous 375 Hysterocarpus traski, Viviparous Perch (male) 379 Hypsypops rubicunda, Garibaldi 382 Pomacentrus leucostictus, Damsel-fish 382
- 30. Glyphisodon marginatus, Cockeye Pilot 383 Microspathodon dorsalis, Indigo Damsel-fish 384 Tautoga onitis, Tautog 384 Tautoga onitis, Tautog 386 Lachnolaimus falcatus, Capitaine or Hogfish 387 Xyrichthys psittacus, Razor-fish 388 Pimelometopon pulcher, Redfish (male) 389 Lepidaplois perditio 389 Pharyngeals of Italian Parrot-fish, Sparisoma cretense. a, Upper; b, Lower 391 Jaws of Parrot-fish, Calotomus xenodon 391 Cryptotomus beryllinus 391 Sparisoma hoplomystax 392 Sparisoma abildgaardi, Red Parrot-fish 392 Jaws of Blue Parrot-fish, Scarus cæruleus 393 Upper pharyngeals of a Parrot-fish, Scarus strongylocephalus 393 Lower pharyngeals of a Parrot-fish, Scarus strongylocephalus 393 Scarus emblematicus 394 Scarus cæruleus, Blue Parrot-fish 394 Scarus vetula, Parrot-fish 395 Halichæres bivittatus, Slippery Dick or Doncella, a fish of the coral-reefs 399 Monodactylus argenteus 397 Psettus sebæ 399 Chætodipterus faber, Spadefish 401 Chætodon capistratus, Butterfly-fish 402 Pomacanthus arcuatus, Black Angel-fish 403 Holacanthus ciliaris, Angel-fish or Isabelita 404 Holacanthus tricolor, Rock Beauty 405
- 31. Zanclus canescens, Moorish Idol 406 Teuthis cæruleus, Blue Tang 407 Teuthis bahianus, Brown Tang 408 Balistes carolinensis, Trigger-fish 412 Osbeckia lævis, File-fish 414 Amanses scopas, Needle-bearing File-fish 414 Stephanolepis hispidus, Common File-fish 415 Lactophrys tricornis, Horned Trunkfish, Cowfish, or Cuckold 416 Ostracion cornutum, Horned Trunkfish 416 Lactophrys bicaudalis, Spotted Trunkfish 416 Lactophrys bicaudalis, Spotted Trunkfish (face view) 417 Lactophrys triqueter, Spineless Trunkfish 417 Lactophrys trigonus, Hornless Trunkfish 418 Skeleton of the Cowfish, Lactophrys tricornis 418 Lagocephalus lævigatus, Silvery Puffer 419 Spheroides spengleri, Puffer, Inflated 420 Spheroides maculatus, Puffer 420 Tetraodon meleagris 421 Tetraodon setosus, Bristly Globefish 422 Diodon hystrix, Porcupine-fish 422 Chilomycterus schœpfi, Rabbit-fish 423 Mola mola, Headfish (adult) 424 Ranzania makua, King of the Mackerel, from Honolulu 425 Sebastes marinus, Rosefish 427 Skull of Scorpænichthys marmoratus 427 Sebastolobus altivelis 428 Sebastodes mystinus, Priest-fish 430 Sebastichthys serriceps 431 Sebastichthys nigrocinctus, Banded Rockfish 432 Scorpæna grandicornis, Lion-fish 433
- 32. Scorpæna mystes, Sea-scorpion 434 Pterois volitans, Lion-fish or Sausolele 435 Emmydrichthys vulcanus, Black Nohu or Poison-fish 436 Snyderina yamanokami 437 Trachicephalus uranoscopus 438 Anoplopoma fimbria, Skilfish 438 Pleurogrammus monopterygius, Atka-fish 439 Hexagrammos decagrammus, Greenling 440 Ophiodon elongatus, Cultus Cod 440 Jordania zonope 442 Astrolytes notospilotus 442 Hemilepidotus jordani, Irish Lord 443 Triglops pingeli 443 Enophrys bison, Buffalo Sculpin 443 Ceratocottus diceraus 444 Elanura forficata 444 Cottus punctulatus, Yellowstone Miller's Thumb 444 Uranidea tenuis, Miller's Thumb 445 Cottus evermanni 445 Cottus gulosus, California Miller's Thumb 446 Myxocephalus niger, Pribilof Sculpin 446 Myxocephalus octodecimspinosus, 18-spined Sculpin 447 Oncocottus quadricornis 447 Blepsias cirrhosus 448 Hemitripterus americanus, Sea-raven 448 Oligocottus maculosus 449 Ereunias grallator 450 Psychrolutes paradoxus, Sleek Sculpin 451 Gilbertidia sigolutes 451 Rhamphocottus richardsoni, Richardson's Sculpin 451
- 33. Stelgis vulsus 451 Draciscus sachi 452 Pallasina barbata, Agonoid-fish 453 Aspidophoroides monopterygius 453 Cyclopterus lumpus, Lumpfish 454 Crystallias matsushimæ, Liparid 454 Neoliparis mucosus, Snailfish 455 Prionotus evolans, Sea-robin 456 Cephalacanthus volitans, Flying Gurnard 457 Peristedion miniatum 457 Philypnus dormitor, Guavina de Rio 460 Eleotris pisonis, Dormeur 460 Dormitator maculatus, Guavina mapo 461 Vireosa hanæ 461 Gobionellus oceanicus, Esmeralda de Mar 461 Pterogobius daimio 462 Aboma etheostoma, Darter Goby 462 Gillichthys mirabilis, Long-jawed Goby 463 Boleophthalmus chinensis, Pond-skipper 466 Periophthalmus barbarus, Mud-skippy 466 Eutæniichthys gillii 467 Leptecheneis naucrates, Sucking-fish or Pegador 468 Rhombochirus osteochir 469 Regalecus russelli, Glesnæs Oarfish 476 Trachypterus rex-salmonorum, Dealfish or King of the Salmon 478 Young Flounder just hatched 482 Pseudopleuronectes americanus, Larval Flounder 483 Larval Stages of Platophrys podas, a Flounder 484 Platophrys lunatus, Peacock Flounder 485 Heterocercal Tail of Young Trout, Salmo fario 486
- 34. Homocercal Tail of a Flounder, Paralichthys californicus 486 Lophopsetta maculata, Window-pane 487 Syacium papillosum, Wide-eyed Flounder 488 Etropus crossotus 489 Hippoglossus hippoglossus, Halibut 492 Paralichthys dentatus, Wide-mouthed Flounder 493 Liopsetta putnami, Eel-back Flounder 494 Platichthys stellatus, Starry Flounder 495 Achirus lineatus, Hog-choker Sole 496 Symphurus plagiusa 498 Pteropsaron evolans 502 Bathymaster signatus 503 Ariscopus iburius 504 Astroscopus guttatus, Star-gazer 505 Neoclinus satiricus, Sarcastic Blenny 507 Gibbonsia evides, Kelp Blenny 508 Blennius cristatus 508 Alticus atlanticus, Rock-skipper 509 Alticus saliens, Lizard-skipper 509 Emblemaria atlantica 510 Scartichthys enosimæ, Fish of the rock-pools of the sacred island of Enoshima, Japan 510 Zacalles bryope 511 Bryostemma tarsodes 511 Exerpes asper 511 Pholis gunnellus, Gunnel 512 Xiphistes chirus 512 Ozorthe dictyogramma 513 Stichæus punctatus 513 Bryostemma otohime 514 Ptilichthys goodei, Quillfish 514
- 35. Blochius longirostris 514 Xiphasia setifera 515 Cryptacanthodes maculatus, Wrymouth 516 Anarhichas lupus, Wolf-fish 517 Skull of Anarrhichthys ocellatus 517 Zoarces anguillaris, Eel-pout 518 Lycodes reticulatus, Eel-pout 519 Lycenchelys verrilli 519 Scytalina cerdale 519 Rissola marginata, Cusk-eel 520 Lycodapus dermatinus 520 Ammodytes americanus, Sand-lance 521 Embolichthys mitsukurii 521 Fierasfer dubius, Pearlfish, Embedded in Pearl 522 Fierasfer acus, Pearlfish 523 Brotula barbata 524 Lucifuga subterranea, Blind Brotula 524 Opsanus pardus, Leopard Toadfish 525 Porichthys porosissimus, Singing Fish (with Many Lateral Lines) 526 Aspasma ciconiæ 530 Caularchus mæandricus, Clingfish 531 Mastacembelus ellipsifer 532 Gadus callarias, Codfish 533 Skull of Haddock, Melanogrammus æglifinus 536 Melanogrammus æglifinus, Haddock 536 Theragra chalcogramma, Pollock 537 Microgadus tomcod, Tomcod 538 Lota maculosa, Burbot 539 Enchelyopus cimbrius, Four-bearded Rockling 539 Merluccius productus, California Hake 540
- 36. Coryphænoides carapinus, showing leptocercal tail 540 Cælorhynchus carminatus, Grenadier 541 Steindachnerella argentea 541 Lophius litulon, Anko or Fishing-frog 545 Cryptopsaras couesi 547 Ceratias holbolli, Deep-sea Angler 548 Caulophryne jordani 548 Pterophryne tumida, Sargassum-fish, one of the Anglers 549 Antennarius nox, Fishing-frog 550 Shoulder-girdle of a Batfish, Ogcocephalus radiatus 551 Antennarius scaber, Frogfish 551 Ogcocephalus vespertilio 552 Ogcocephalus vespertilio, Batfish 553 Ogcocephalus vespertilio, Batfish 553
- 37. ERRATA[1] Vol. II Page xviii, line 7, for Ophicæphalus read Ophicephalus xviii, " 37, for Mononactylus read Monodactylus xix, " 33, for Trachicephales read Trachicephalus xx, " 37, for Regaleaus glesneacsanius read Regalecus russelli xxi, " 2, for Etopus read Etropus xxi, " 35, for Zoacres read Zoarces 1, " 7, for jaws read jaw 14, " 9, for hetercoercal read heterocercal 136, " 3, for Evermannellus read Evermannella 170, " 11, for the fin read the dorsal fin 171, " 10, for have read has 303, legend, for Lacepède read Lacépède 307, line 14, for vertebrate read vertebral 311, " 12, not clearly stated. The air-bladder is least developed in those species which cling closest to the bottom of the stream 350, legend, for Apomotes read Apomotis 355, line 18, for ours read our 357, " 14, for chætodon read Chætodon 358, " 17, for Scriænidæ read Sciænidæ
- 38. 360, " 14, for Percesoces read Percesoces 409, " 16, for naseus read Naseus 419, " 23, for of the generic of this group read separating the group into genera 440, " 17, for Chinnook read Chinook 459, " 24, for but the most read but most 459, " 25, for thme read them 467, " 14, for Typhogobius read Typhlogobius 472, lines 34, 35, omit "but never in the United States". Specimens of Regalecus have been taken at Anclote Key, Florida, and at the Tortugas. 580, col. 3, line 17, for 165 read 105 The adoption of the Code of the International Congress of Zoology necessitates a few changes in generic names used in this book. Thus Amia (ganoid) becomes Amiatus Apogon becomes Amia Scarus becomes Callyodon Teuthis becomes Hepatus Acanthurus becomes Monoceros Paramia becomes Cheilodipterus Centropomus (Oxylabrax) remains Centropomus Lucioperca (Centropomus) becomes Sander Pomatomus (Cheilodipterus) remains Pomatomus Nomeus (Gobiomorus) remains Nomeus Galeus (Galeorhinus) remains Galeus Carcharias (Carcharhinus) remains Carcharias 1. For most of this list of errata I am indebted to the kindly interest of Dr. B. W. Evermann.
- 39. CHAPTER I THE GANOIDS ubclass Actinopteri.—In our glance over the taxonomy of the earlier Chordates, or fish-like vertebrates, we have detached from the main stem one after another a long series of archaic or primitive types. We have first set off those with rudimentary notochord, then those with retrogressive development who lose the notochord, then those without skull or brain, then those without limbs or lower jaw. The residue assume the fish-like form of body, but still show great differences among themselves. We have then detached those without membrane-bones, or trace of lung or air-bladder. We next part company with those having the air-bladder a veritable lung, and those with an ancient type of paired fins, a jointed axis fringed with rays, and those having the palate still forming the upper jaw. We have finally left only those having fish-jaws, fish-fins, and in general the structure of the modern fish. For all these in all their variety, as a class or subclass, the name Actinopteri, or Actinopterygii, suggested by Professor Cope, is now generally adopted. The shorter form, Actinopteri, being equally correct is certainly preferable. This term (ακτίς, ray; πτερόν or πτερύξ, fin) refers to the structure of the paired fins. In all these fishes the bones supporting the fin-rays are highly specialized and at the same time concealed by the general integument of the body. In general two bones connect the pectoral fin with the shoulder-girdle. The hypercoracoid is a flat square bone, usually perforated by a foramen. Lying below it and parallel with it is the irregularly formed hypocoracoid. Attached to them is a row of bones, the actinosts, or pterygials, short, often hour-glass-shaped,
- 40. which actually support the fin-rays. In the more specialized forms, or Teleosts, the actinosts are few (four to six) in number, but in the more primitive types, or Ganoids, they may remain numerous, a reminiscence of the condition seen in the Crossopterygians, and especially in Polypterus. Other variations may occur; the two coracoids sometimes are imperfect or specially modified, the upper sometimes without a foramen, and the actinosts may be distorted in form or position.
- 41. Fig. 1.—Shoulder-girdle of a Flounder, Paralichthys californicus (Ayres). The Series Ganoidei.—Among the lower Actinopteri many archaic traits still persist, and in its earlier representatives the group approaches closely to the Crossopterygii, although no forms actually intermediate are known either living or fossil. The great group of Actinopteri may be divided into two series or subclasses, the Ganoidei, or Chrondrostei, containing those forms, mostly extinct, which retain archaic traits of one sort or another, and the Teleostei, or bony fishes, in which most of the primitive characters have disappeared. Doubtless all of the Teleostei are descended from a ganoid ancestry. Even among the Ganoidei, as the term is here restricted, there remains a very great variety of form and structure. The fossil and existing forms do not form continuous series, but represent the tips and remains of many diverging branches perhaps from some Crossopterygian central stock. The group constitutes at least three distinct orders and, as a whole, does not admit of perfect definition. In most but not all of the species the tail is distinctly and obviously heterocercal, the lack of symmetry of the tail in some Teleosts being confined to the bones and not evident without dissection. Most of the Ganoids have the skeleton still cartilaginous, and in some it remains in a very primitive condition. Usually the Ganoids have an armature of bony plates, diamond-shaped, with an enamel like that developed on the teeth. In all of them the pectoral fin has numerous basal bones or actinosts. All of them have the air-bladder highly developed, usually cellular and functional as a lung, but connecting with the dorsal side of the gullet, not with the ventral side as in the Dipnoans. In all living forms there is a more or less perfect optic chiasma. These ancient forms retain also the many valves of the arterial bulb and the spiral valve of the intestines found in the more archaic types of fishes. But traces of some or all of these structures are found in some bony fishes, and their presence in the Ganoids by
- 42. no means justifies the union of the Ganoids with the sharks, Dipnoans, and Crossopterygians to form a great primary class, Palæichthyes, as proposed by Dr. Günther. Almost every form of body may be found among the Ganoids. In the Mesozoic seas these fishes were scarcely less varied and perhaps scarcely less abundant than the Teleosts in the seas of to-day. They far exceed the Crossopterygians in number and variety of forms. Transitional forms connecting the two groups are thus far not recognized. So far as fossils show, the characteristic actinopterous fin with its reduced and altered basal bones appeared at once without intervening gradations. The name Ganoidei (γάνος, brightness; εἶδος, resemblance), alluding to the enameled plates, was first given by Agassiz to those forms, mostly extinct, which were covered with bony scales or hard plates of one sort or another. As the term was originally defined, mailed catfishes, sea-horses, Agonidæ, Arthrodires, Ostracophores, and other wholly unrelated types were included with the garpikes and sturgeons as Ganoids. Most of these intruding forms among living fishes were eliminated by Johannes Müller, who recognized the various archaic characters common to the existing forms after the removal of the mailed Teleosts. Still later Huxley separated the Crossopterygians as a distinct group, while others have shown that the Ostracophori and Arthrodira should be placed far from the garpike in systematic classification. Cope, Woodward, Hay, and others have dropped the name Ganoid altogether as productive of confusion through the many meanings attached to it. Others have kept it as a convenient group name for the orders of archaic Actinopteri. For these varied and more or less divergent forms it seems convenient to retain it. As an adjective "ganoid" is sometimes used as descriptive of bony plates or enameled scales, some-in the sense of archaic, as applied to fishes. Are the Ganoids a Natural Group?—Several writers have urged that the Ganoidei, even as thus restricted, should not be considered as a natural group, whether subclass, order, or group of orders. The reasons for this view in brief are the following:
- 43. 1. The group is heterogeneous. The Amiidæ differ more from the other Ganoids than they do from the herring-like Teleosts. The garpikes, sturgeons, paddle-fishes likewise diverge widely from each other and from the Palæoniscidæ and the Platysomidæ. Each of the living families represents the residue or culmination of a long series, in some cases advancing, as in the case of the bowfin, sometimes perhaps degenerating, as in the case of the sturgeons. 2. Of the traits possessed in common by these forms, several (the cellular air-bladder, the many valves in the heart, the spiral valve in the intestine, the heterocercal tail) are all possessed in greater or less degree by certain Isospondyli or allies of the herring. All these characters are still better developed in Crossoptergyii and Dipneusti, and each one disappears by degrees. Of the characters drawn from the soft parts we can know nothing so far as the extinct Ganoids are concerned. 3. The optic chiasma, thus far characteristic of Ganoids as distinct from Teleosts, may have no great value. It is urged that in closely related species of lizards some have the optic chiasma and others do not. This, however, proves nothing as to the value of the same character among fishes. 4. The transition from Ganoids to Teleosts is of much the same character as the transition from spiny-rayed to soft-rayed fishes, or that from fishes with a duct to the air-bladder to those without such duct. Admitting all this, it is nevertheless natural and convenient to retain the Ganoidei (or Chrondrostei if the older name be discarded on account of the many meanings attached to it) as a group equivalent to that of Teleostei within the class or subclass of Actinopteri. It comprises the transitional forms between the Crossopterygii and the bony fishes, and its members are especially characteristic of the Mesozoic age, ranging from the Devonian to the present era. Of the extensive discussion relating to this important question we may quote two arguments for the retention of the subclass of
- 44. Ganoids, the first by Francis M. Balfour and William Kitchen Parker, the second from the pen of Theodore Gill. Balfour and Parker ("Structure and Development of Lepidosteus," pp. 430-433) thus discuss the Systematic Position of Lepidosteus.—"Alexander Agassiz concludes his memoir on the development of Lepidosteus by pointing out that in spite of certain affinities in other directions this form is 'not so far removed from the bony fishes as has been supposed.' Our own observations go far to confirm Agassiz's opinion. "Apart from the complete segmentation, the general development of Lepidosteus is strikingly Teleostean. In addition to the general Teleostean features of the embryo and larva, which can only be appreciated by those who have had an opportunity of practically working at the subject, we may point to the following developmental features[2] as indicative of Teleostean affinities: "(1) The formation of the nervous system as a solid keel of the epiblast. "(2) The division of the epiblast into a nervous and epidermic stratum. "(3) The mode of development of the gut. "(4) The mode of development of the pronephros; though the pronephros of Lepidosteus has primitive characters not retained by Teleostei. "(5) The early stages in the development of the vertebral column. 2. The features enumerated above are not in all cases confined to Lepidosteus and Teleostei, but are always eminently characteristic of the latter. "In addition to these, so to speak, purely embryonic characters there are not a few important adult characters: "(1) The continuity of the oviducts with the genital glands. "(2) The small size of the pancreas, and the presence of numerous so-called pancreatic cæca.
- 45. "(3) The somewhat coiled small intestine. "(4) Certain characters of the brain, e.g., the large size of the cerebellum; the presence of the so-called lobi inferiores on the infundibulum, and of tori semi-circulares in the mid-brain. "In spite of the undoubtedly important list of features to which we have just called attention, a list containing not less important characters, both embryological and adult, separating Lepidosteus from the Teleostei, can be drawn up: "(1) The character of the truncus arteriosus. "(2) The fact of the genital ducts joining the ureters. "(3) The presence of vasa efferentia in the male carrying the semen from the testes to the kidney, and through the tubules of the latter into the kidney-duct. "(4) The presence of a well-developed opercular gill. "(5) The presence of a spiral valve; though this character may possibly break down with the extension of our knowledge. "(6) The typical Ganoid characters of the thalamencephalon and the cerebral hemispheres. "(7) The chiasma of the optic nerves. "(8) The absence of a pecten, and presence of a vascular membrane between the vitreous humor and the retina. "(9) The opisthocœlous form of the vertebræ. "(10) The articulation of the ventral parts of the hæmal arches of the tail with the processes of the vertebral column. "(11) The absence of a division of the muscles into dorso-lateral and ventro-lateral divisions. "(12) The complete segmentation of the ovum. "The list just given appears to us sufficient to demonstrate that Lepidosteus cannot be classed with the Teleostei; and we hold that
- 46. Müller's view is correct, according to which Lepidosteus is a true Ganoid. "The existence of the Ganoids as a distinct group has, however, recently been challenged by so distinguished an ichthyologist as Günther, and it may therefore be well to consider how far the group as defined by Müller is a natural one for living forms, and how far recent researches enable us to improve upon Müller's definitions. In his classical memoir the characters of the Ganoids are thus shortly stated: "'These fishes are either provided with plate-like angular or rounded cement-covered scales, or they bear osseous plates, or are quite naked. The fins are often, but not always, beset with a double or single row of spinous plates or splints. The caudal fin embraces occasionally in its upper lobe the end of the vertebral column, which may be prolonged to the end of the upper lobe. Their double nasal openings resemble those of Teleostei. The gills are free, and lie in a branchial cavity under an operculum, like those of Teleostei. Many of them have an accessory organ of respiration, in the form of an opercular gill, which is distinct from the pseudobranch, and can be present together with the latter; many also have spiracles like Elasmobranchii. They have many valves in the stem of the aorta like the latter, also a muscular coat in the stem of the aorta. Their ova are transported from the abdominal cavity by oviducts. Their optic nerves do not cross each other. The intestine is often provided with a spiral valve, like Elasmobranchii. They have a swimming-bladder with a duct, like many Teleostei. Their pelvic fins are abdominal. "'If we include in a definition only those characters which are invariable, the Ganoids may be shortly defined as being those fish with numerous valves to the stem of the aorta, which is also provided with a muscular coat, with free gills, and an operculum, and with abdominal pelvic fins.' "To these distinctive characters he adds, in an appendix to his paper, the presence of the spiral valve, and the absence of a processus falciformis and a choroid gland.
- 47. "To the distinctive set of characters given by Müller we may probably add the following: "(1) Oviducts and urinary ducts always unite, and open by a common urogenital aperture behind the anus. "(2) Skull hyostylic. "(3) Segmentation complete in the types so far investigated, though perhaps Amia may be found to resemble the Teleostei in this particular. "(4) A pronephros of the Teleostean type present in the larva. "(5) Thalamencephalon very large and well developed. "(6) The ventricle in the posterior part of the cerebrum is not divided behind into lateral halves, the roof of the undivided part being extremely thin. "(7) Abdominal pores always present. "The great number of characters just given are amply sufficient to differentiate the Ganoids as a group; but, curiously enough, the only characters, amongst the whole series which have been given, which can be regarded as peculiar to the Ganoids are (1) the characters of the brain, and (2) the fact of the oviducts and kidney-ducts uniting together and opening by a common pore to the exterior. "This absence of characters peculiar to the Ganoids is an indication of how widely separated in organization are the different members of this great group. "At the same time, the only group with which existing Ganoids have close affinities is the Teleostei. The points they have in common with the Elasmobranchii are merely such as are due to the fact that both retain numerous primitive vertebrate characters,[3] and the gulf which really separates them is very wide. 3. As instances of this we may cite (1) the spiral valve; (2) the frequent presence of a spiracle; (3) the frequent presence of a communication between the pericardium and the body-cavity; (4) the heterocercal tail.
- 48. "There is again no indication of any close affinity between the Dipnoans and, at any rate, existing Ganoids. "Like the Ganoids, the Dipnoans are no doubt remnants of a very primitive stock; but in the conversion of the air-bladder into a true lung, the highly specialized character of their limbs,[4] their peculiar autostylic skulls, the fact of their ventral nasal openings leading directly into the mouth, their multi-segmented bars (interspinous bars) directly prolonged from the neural and hæmal and supporting the fin-rays of the unpaired dorsal and ventral fins, and their well- developed cerebral hemispheres, very unlike those of Ganoids and approaching the Amphibian type, they form a very well-defined group and one very distinctly separated from the Ganoids. 4. Vide F. M. Balfour, "On the Development of the Skeleton of the Paired Fins of Elasmobranchs," Proc. Zool. Soc., 1881. "No doubt the Chondrostean Ganoids are nearly as far removed from the Teleostei as from the Dipnoans, but the links uniting these Ganoids with the Teleostei have been so fully preserved in the existing fauna of the globe that the two groups almost run into each other. If, in fact, we were anxious to make any radical change in the ordinary classification of fishes, it would be by uniting the Teleostei and Ganoids, or rather constituting the Teleostei into one of the subgroups of the Ganoids, equivalent to the Chondrostei. We do not recommend such an arrangement, which in view of the great preponderance of the Teleostei amongst living fishes would be highly inconvenient, but the step from Amia to the Teleostei is certainly not so great as that from the Chondrostei to Amia, and is undoubtedly less than that from the Selachii to the Holocephali." Gill on the Ganoids as a Natural Group.—Dr. Gill observes ("Families of Fishes," 1872): "The name Ganoides (or Ganiolepedoti) was originally framed by Prof. Agassiz as an ordinal term for fishes having the scales (when present) angular and covered with enamel; and in the group so characterized were combined the Ganoids of subsequent authors as well as the Teleostean orders Plectognathi, Lophobranchii, and Nematognathi, and (subsequently) the genus
- 49. Sudis (Arapaima), the last being regarded as a Cœlacanth. The group has not been accepted with these limits or characters. "But the researches of Prof. Johannes Müller on the anatomy and classification of the fishes culminated at length in his celebrated memoirs on those fishes for which he retained the ordinal name Ganoidei; those memoirs have left an impression on ichthyology perhaps more decided than made by any other contributions to science, and that published in extenso will ever be classical; numerous as have been the modifications since introduced into the system, no forms except those recognized by Müller (unless it be Dipnoi) have been interjected since among the Ganoids. "It has been objected that the Ganoids do not constitute a natural group, and that the characters (i.e., chiasma of optic nerves and multivalvular bulbus arteriosus) alleged by Müller to be peculiar to the teleostomous forms combined therein are problematical, and only inferentially supposed to be common to the extinct Ganoids so called, and, finally, such objections couched in too strong language have culminated in the assertion that the characters in question are actually shared by other physostome fishes. "No demonstration, however, has been presented as yet that any physostome fishes do really have the optic chiasma and multivalvular bulbus arteriosus, and the statement to the contrary seems to have been the result of a venial misapprehension of Prof. Kner's statements, or the offspring of impressions left on the memory by his assertions, in forgetfulness of his exact words. "But Prof. Kner, in respect to the anatomical characters referred to, merely objects: (1) that they are problematical, are not confirmable for the extinct types, and were probably not existent in certain forms that have been referred to the Ganoids; (2) the difference in number of the valves of the bulbus arteriosus among recent Ganoids is so great as to show the unreliability of the character; (3) a spiral valve is developed in the intestine of several osseous fishes ('genera of the so-called intermediate clupeoid groups'), as well as in Ganoids; and
- 50. (4) the chiasma of the optic nerves in no wise furnishes a positive character for the Ganoids. "It will be noticed that all these objections (save in the case of the intestinal spiral valve) are hypothetical and vague. The failure of the intestinal spiral valve, as a diagnostic character, has long been conceded, and in this case only have the forms that prove the failure been referred to; in the other cases, where it would be especially desirable to have indicated the actual types falsifying the universality or exclusiveness of the characters, they have not been referred to, and the objections must be met as if they were not known to exist. "(1) The characters in question are, in the sense used, problematical, inasmuch as no examination can be made of the soft parts of extinct forms, but with equal force may it be urged that any characters that have not been or cannot be directly confirmed are problematical in the case of all other groups (e.g., mammals), and it can only be replied that the coordination of parts has been so invariably verified that all probabilities are in favor of similar coordination in any given case. "(2) There is doubtless considerable difference in the number of valves of the bulbus arteriosus among the various Ganoids, and even among the species of a single family (e.g., Lepidosteidæ), but the character of Ganoids lies not in the number, more or less, but in the greater number and relations (in contradistinction to the opposite pair of the Teleosts) in conjunction with the development of a bulbus arteriosus. In no other forms of Teleostomes have similar relations and structures been yet demonstrated. "(3) The failure of the spiral intestinal valve has already been conceded, and no great stress has ever been laid on the character. "(4) The chiasma of the optic nerves is so common to all the known Ganoids, and has not been found in those forms (e.g., Arapaima, Osteoglossum, and Clupeiform types) agreeing with typical physostome Teleosts in the skeleton, heart, etc., but which at the same time simulate most certain Ganoids (e.g., Amia) in form.
- 51. "Therefore, in view of the evidence hitherto obtained, the arguments against the validity of title, to natural association, of the Ganoids, have to meet the positive evidence of the coordinations noted; the value of such characteristics and coordinations can only be affected or destroyed by the demonstration that in all other respects there is (1) very close agreement of certain of the constituents of the subclass with other forms, and (2) inversely proportionate dissimilarity of those forms from any (not all) other of the Ganoids, and consequently evidence ubi plurima nitent against the taxonomic value of the characters employed for distinction. "And it is true that there is a greater superficial resemblance between the Hyoganoids (Lepisosteus, Amia, etc.) and ordinary physostome Teleosts than between the former and the other orders of Ganoids, but it is equally true that they agree in other respects than in the brain and heart with the more generalized Ganoids. They all have, for example, (1) the paraglenal elements undivided (not disintegrated into hypercoracoid, hypocoracoid, and mesocoracoid); (2) a humerus (simple or divided, that is, differentiated into metapterygium and mesopterygium); and (3) those with ossified skeletons agree in the greater number of elements in the lower jaw. Therefore, until these coordinates fail, it seems advisable to recognize the Ganoids as constituents of a natural series; and especially on account of the superior taxonomic value of modifications of the brain and heart in other classes of vertebrates, for the same reason, and to keep prominently before the mind the characters in question, it appears also advisable to designate the series, until further discovery, as a subclass. "But it is quite possible that among some of the generalized Teleosts at least traces of some of the characters now considered to be peculiar to the Ganoids may be discovered. In anticipation of such a possibility, the author had at first discarded the subclass, recognizing the group only as one of the 'superorders' of the Teleostomes, but reconsideration convinces him of the propriety of classification representing known facts and legitimate inferences rather than too much anticipation.
- 52. "It is remembered that all characters are liable to fail with increasing knowledge, and the distinctness of groups are but little more than the expressions of our want of knowledge of the intermediate forms; it may in truth be said that ability to segregate a class into well- defined groups is in ratio to our ignorance of all the terms."
- 53. CHAPTER II THE GANOIDS—Continued lassification of Ganoids.—The subdivision of the series of Ganoidei into orders offers great difficulty from the fact of the varying relationships of the members of the group and the fact that the great majority of the species are known only from broken skeletons preserved in the rocks. It is apparently easy to separate those with cartilaginous skeletons from those with these bones more or less ossified. It is also easy to separate those with bony scales or plates from those having the scales cycloid. But the one type of skeleton grades into the other, and there is a bony basis even to the thinnest of scales found in this group. Among the multitude of names and divisions proposed we may recognize six orders, for which the names Lysopteri, Chondrostei, Selachostomi, Pycnodonti, Lepidostei, and Halecomorphi are not inappropriate. Each of these seems to represent a distinct offshoot from the first primitive group. Order Lysopteri.—In the most primitive order, called Lysopteri (λυσός, loose; πτερόν, fin) by Cope, Heterocerci by Zittel and Eastman, and the "ascending series of Chondrostei" by Woodward, we find the nearest approach to the Chondropterygians. In this order the arches of the vertebræ are more or less ossified, the body is more or less short and deep, covered with bony dermal plates. The opercular apparatus is well developed, with numerous branchiostegals. Infraclavicles are present, and the fins provided with fulcra. Dorsal and anal fins are present, with rays more numerous than their supports; ventral fin with basal supports which
- 54. are imperfectly ossified; caudal fin mostly heterocercal, the scales mostly rhombic in form. All the members of this group are now extinct. The Palæoniscidæ.—The numerous genera of this order are referred to three families, the Palæoniscidæ, Platysomidæ, and Dictyopygidæ; a fourth family, Dorypteridæ, of uncertain relations, being also tentatively recognized. The family of Palæoniscidæ is the most primitive, ranging from the Devonian to the Lias, and some of them seem to have entered fresh waters in the time of the coal- measures. These fishes have the body elongate and provided with one short dorsal fin. The tail is heterocercal and the body covered with rhombic plates. Fulcra or rudimentary spine-like scales are developed on the upper edge of the caudal fin in most recent Ganoids, and often the back has a median row of undeveloped scales. A multitude of species and genera are recorded. A typical form is the genus Palæoniscum,[5] with many species represented in the rocks of various parts of the world. The longest known species is Palæoniscum frieslebenense from the Permian of Germany and England. Palæoniscum magnum, sixteen inches long, occurs in the Permian of Germany. From Canobius, the most primitive genus, to Coccolepis, the most modern, is a continuous series, the suspensorium of the lower jaw becoming more oblique, the basal bones of the dorsal fewer, the dorsal extending farther forward, and the scales more completely imbricate. Other prominent genera are Amblypterus, Eurylepis, Cheirolepis, Rhadinichthys, Pygopterus, Elonichthys, Ærolepis, Gyrolepis, Myriolepis, Oxygnathus, Centrolepis, and Holurus. 5. This word is usually written Palæoniscus, but Blainville, its author (1818), chose the neuter form.
- 55. Fig. 2.—Palæoniscum frieslebenense Blainville. Family Palæoniscidæ. (After Zittel.) The Platysomidæ.—The Platysomidæ are different in form, the body being deep and compressed, often diamond-shaped, with very long dorsal and anal fins. In other respects they are very similar to the Palæoniscidæ, the osteology being the same. The Palæoniscidæ were rapacious fishes with sharp teeth, the Platysomidæ less active, and, from the blunter teeth, probably feeding on small animals, as crabs and snails. The rhombic enameled scales are highly specialized and held together as a coat of mail by peg-and-socket joints. The most extreme form is Platysomus, with the body very deep. Platysomus gibbosus and other species occur in the Permian rocks of Germany. Cheirodus is similar to Platysomus, but without ventral fins. Eurynotus, the most primitive genus, is remarkable for its large pectoral fins. Eurynotus crenatus occurs in the Subcarboniferous of Scotland. Other genera are Mesolepis, Globulodus, Wardichthys, and Cheirodopsis.
- 56. Fig. 3.—Eurynotus crenatus Agassiz, restored. Carboniferous. Family Platysomidæ. (After Traquair.) Some of the Platysomidæ have the interneural spines projecting through the skin before the dorsal fin. This condition is found also in certain bony fishes allied to the Carangidæ. The Dorypteridæ.—Dorypterus hoffmani, the type of the singular Palæozoic family of Dorypteridæ, with thoracic or sub-jugular many- rayed ventrals, is Stromateus-like to all appearance, with distinct resemblances to certain Scombroid forms, but with a heterocercal tail like a ganoid, imperfectly ossified back-bone, and other very archaic characters. The body is apparently scaleless, unlike the true Platysomidæ, in which the scales are highly developed. A second species, Dorypterus althausi, also from the German copper shales, has been described. This species has lower fins than Dorypterus hoffmani, but may be the adult of the same type. Dorypterus is regarded by Woodward as a specialized offshoot from the Platysomidæ. The many-rayed ventrals and the general form of the body and fins suggest affinity with the Lampridæ.
- 57. Fig. 4.—Dorypterus hoffmani Germar, restored. (After Hancock and Howse.) Dictyopygidæ.—In the Dictyopygidæ (Catopteridæ), the body is gracefully elongate, less compressed, the heterocercal tail is short and abruptly turned upwards, the teeth are sharp and usually hooked, and the bony plates well developed. Of this group two genera are recognized, each containing numerous species. In Redfieldius (= Catopterus Redfield, not of Agassiz) the dorsal is
- 58. inserted behind the anal, while in Dictyopyge this is not the case. Redfieldius gracilis and other species are found in the Triassic of the Connecticut River. Dictyopyge macrura is found in the same region, and Dictyopyge catoptera and other species in Europe. Order Chondrostei.—The order Chondrostei (χόνδρος, cartilage; ὀστέον, bone), as accepted by Woodward, is characterized by the persistence of the notochord in greater or less degree, the endoskeleton remaining cartilaginous. In all, the axonosts and baseosts of the median fins are arranged in simple regular series and the rays are more numerous than the supporting elements. The shoulder-girdle has a pair of infraclavicular plates. The pelvic fins have well-developed baseosts. The branchiostegals are few or wanting. In the living forms, and probably in all others, a matter which can never be ascertained, the optic nerves are not decussating, but form an optic chiasma, and the intestine is provided with a spiral valve. In all the species there is one dorsal and one anal fin, separate from the caudal. The teeth are small or wanting, the body naked or covered with bony plates; the caudal fin is usually heterocercal, and on the tail are rhombic plates. To this order, as thus defined, about half of the extinct Ganoids belong, as well as the modern degenerate forms known as sturgeons and perhaps the paddle-fishes, which are apparently derived from fishes with rhombic enameled scales. The species extend from the Upper Carboniferous to the present time, being most numerous in the Triassic. At this point in Woodward's system diverges a descending series, characterized as a whole by imperfect squamation and elongate form, this leading through the synthetic type of Chondrosteidæ to the modern sturgeon and paddle-fish, which are regarded as degenerate types. The family of Saurorhynchidæ contains pike-like forms, with long jaws, and long conical teeth set wide apart. The tail is not heterocercal, but short-diphycercal; the bones of the head are covered with enamel, and those of the roof of the skull form a continuous shield. The opercular apparatus is much reduced, and
- 59. there are no branchiostegals. The fins are all small, without fulcra, and the skin has isolated longitudinal series of bony scutes, but is not covered with continuous scales. The principal genus is Saurorhynchus (= Belonorhynchus; the former being the earlier name) from the Triassic. Saurorhynchus acutus from the English Triassic is the best known species. The family of Chondrosteidæ includes the Triassic precursors of the sturgeons. The general form is that of the sturgeon, but the body is scaleless except on the upper caudal lobe, and there are no plates on the median line of the skull. The opercle and subopercle are present, the jaws are toothless, and there are a few well-developed caudal rays. The caudal has large fulcra. The single well-known species of this group, Chondrosteus acipenseroides, is found in the Triassic rocks of England and reaches a length of about three feet. It much resembles a modern sturgeon, though differing in several technical respects. Chondrosteus pachyurus is based on the tail of a species of much larger size and Gyrosteus mirabilis, also of the English Triassic, is known from fragments of fishes which must have been 18 to 20 feet in length. Fig. 5.—Chondrosteus acipenseroides Egerton. Family Chondrosteidæ. (After Woodward.) The sturgeons constitute the recent family of Acipenseridæ, characterized by the prolonged snout and toothless jaws and the presence of four barbels below the snout. In the Acipenseridæ there
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