III. FISHES, LIVING AND FOSSIL. 



AN INTRODUCTORY STUDY. 



BY 



BASHFORD DEAN, PH.D. COLUMBIA, 



Instructor in Biology, Columbia College. 



This work has been prepared to meet the needs of the gen- 

 eral student for a concise knowledge of the Fishes. It contains 

 a review of the four larger groups of the strictly fishlike forms, 

 Sharks, Chimaeroids, Teleostomes, and the Dipnoaus, and adds 

 to this a chapter on the Lampreys. It presents in figures the 

 prominent members, living and fossil, of each group; illustrates 

 characteristic structures; adds notes upon the important phases 

 of development, and formulates the views of investigators as to 

 relationships and descent. 



The recent contributions to the knowledge of extinct Fishes 

 are taken into special account in the treatment of the entire 

 subject, and restorations have been attempted, as of Diuichthys, 

 Ctenodus, and Cladoselache. 



The writer has also indicated diagram matically, as far as 

 generally accepted, the genetic relationships of fossil and living 

 forms. 



The aim of the book has been mainly to furnish the student 

 with a well-marked ground-plan of Ichthyology, to enable him to 

 better understand special works, such as those of Smith Wood- 

 ward and Grimther. The work is fully illustrated, mainly from 

 the writer's original pen-drawings. 



TABLE OF CONTENTS. 



CHAPTER 



I. FISHES. Their Essential Characters. Sharks, Chimaeroids, Teleo- 

 stomes, and Lung-fishes. Their Appearance in Time and their 

 Distribution. 



II. THE LAMPREYS. Their Position with Reference to Fishes. Bdel- 

 lostoma, Myxine, Petromyzon, Palaeospondylus. 



III. THE SHAHK GROUP. Anatomical Characters. Its Extinct Members, 



Acauthodian, Cladoselachid, Xenacanthid, Cestracionts. 



IV. CHIMAEROIDS. Structures of Callorhyuchus and Chimaera. Squalo- 



raja and Myriacanthus. Life-habits and Probable Relationships. 

 V. TELEOSTOMES. The Forms of Recent " Ganoids." Habits and Dis- 

 tribution. The Relations of Prominent Extinct Forms. Crosso- 

 pterygiaus. Typical " Bony Fishes. " 



VI. THE EVOLUTION OF THE GROUPS OF FISHES. Aquatic Metamerism. 



Numerical Lines. Evolution of Gill-cleft Characters, Paired and 



Unpaired Fins, Aquatic Sense-organs. 

 VII. THE DEVELOPMENT OF FISHES. Prominent Features in Embryonic 



and Larval Development of Members of each Group. Summaries. 



