422 The History of Ichthyology 



j\lrs. Rosa Smith Eigenmann, Dr. Joseph Swain, Wilbur Wilson 

 Thnburn (1859-99), Fi-ank Cramer, Alvin Seale, Albert Jeffer- 

 son AVoolman, Phihp H. Kirsch (1860-1902), Cloudsley Rutter 

 (died 1903), Robert Edward Snodgrass, James Francis Abbott, 

 Arthur White Greeley, Edmund Heller, Henry Weed Fowler, 

 Keinosuke Otaki, ]\Iichitaro Sindo, and Richard Crittenden 

 McGregor. 



Other facts and conclusions of importance haA-e been con- 

 tributed by various persons with whom ichthyology has been 

 an incident rather than a matter of central importance. 



The Fossil Fishes.* — The study of fossil fishes was begun sys- 

 tematically during the first decades of the nineteenth century, 

 for it was then realized that of fossils of backboned animals, 

 fishes were the only ones which could be determined from early 

 Palaeozoic to recent horizons, and that from the diversity of 

 their forms they could serve as reliable indications of the age 

 of rocks. ^Vt a later time, when the CA'olution of vertebrates 

 began to be studied, fishes were examined with especial care 

 with a A-icw of determining the ancestral line of the Amphibians. 

 The earliest work upon fossil fishes is, as one would naturally 

 expect, of a purely systematic value. Anatomical observa- 

 tirjns Avere scanty and crude, but as the material for study 

 increased, a more satisfactory knowledge was gained of the 

 structures of the various major groups of fishes; and finally 

 by a comparison of anatomical results important light came 

 to be thrown upon more fundamental problems. 



The study of fossil fishes can be divided for convenience 

 into three periods: d) That which terminated in the luag- 

 nitui opus of J^ouis Agassiz ; (II) that of the S3'stematists whose 

 major works appeared between 1845 and the* recent publica- 

 tion of the Catalogue of Fossil Fishes of the British iluseum 

 (from this period date many important anatomical observa- 

 tions); and (III) that of morphological work, roughh^ from 

 1870 to the present. During this period detailed considera- 

 tion has been giA-en to the ph}dogeny oi special structures, 

 to the proljablc lines of descent of the groups of fossil fishes, 

 and to the relationships of terrestrial to aquatic vertebrates. 



* For these paragraphs on the history of the study of fossil fishes th( 

 writer is indebted t.. the kind interest of Professor Bashford Dean. 



