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, Ohimaeroids, Teleostomes, and the Dipnoans, aud 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 imp)ortant 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 Dinichthys, 

 Ctenodus, and Cladoselache. 



The writer has also indicated diagrammatically, 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 Griinther. The work is fully illustrated, mainly from 

 the writer's original pen-drawings. 



TABLE OF CONTENTS. 



CHAPTER 



I. Fishes. Their Essenlial Cbaiacters. Sharks, Chimaeroids, Teleo- 

 stomes, and Luug-lishes. Their Appearance in Time and their 

 Distribution. 

 II. The Lampreys. Their Position with Reference to Fishes. Bdel- 



lostoma, Myxiue, Petromj'zou, Palaeospondylus. 

 IIL The Sh.a.kk Gkoup. Anatomical Characters. Its Extinct Members, 



Acauthodian, Cladoselachid, Xenacanthid, Cestraciouts. 

 IV. Chimaeroids. Structures of Callorhyucbus and Chimaera. Squalo- 

 raja and Myriacanthus. Life-habits and Probable Relationships. 

 V. Teleostomes. Tlie Forms of Recent " Ganoids." Habits aud Dis- 

 tribution. The Relations of Prominent Extinct Forms. Crosso- 

 pterygians. Typical " Bony Fishes. " 



VI. The Evolution op the Groups op Fishes. Aq\iatic Metamerism. 



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



Unpaired Fins, Aquatic Sense-organs. 

 Vn. The Development op Fishes. Prominent Features in Embr3'onic 



and Larval Development of Members of each Gioup. Summaries. 



