LIFE AND WORKS OF COPE. XUI 



"The most interesting feature of the Crossopterygii consists in the 

 mode of specialization of their fins ; and this, as pointed out by 

 Cope, affords a satisfactory basis for the definition of the suborders." 

 (Ibid, Pt. II, p. xxi. ) 



The objections of Kner and others were reinforced by 

 Cope with arguments derived from the osseous parts ; and 

 he concluded that it was "evident that the subclass Ganoi- 

 dea cannot be maintained". He then proceeded to the 

 consideration of the value of other characters and at length 

 resolved to recombine the scattered elements of the great 

 class of Pisces, limited by the exclusion of the Leptocar- 

 dians and Marsipobranchs, into five primary subdivisions 

 or subclasses. 



In these papers he therefore boldly abandons the group 

 of Ganoids and redistributes the fishes into five great sub- 

 classes, namely, the Holocephali (Bonaparte, 1832-41), Se- 

 lachii (Cuvier, 1817), the Dipnoi (Miiller), the Crossopterygii 

 (Huxley) with paired fins arranged so as to form a fringe 

 around a central lobe, and the Adinopteryi. He showed 

 that each of these forms a natural group, and the differen- 

 tiation between each and its nearest of kin is on the whole 

 well marked. Second to this emphasis upon fin structure 

 was that upon the jaw structure, or the union of the upper 

 jaw with the skull, which separates the Holocephali from the 

 Selachii. Third, he employs the modifications of the res- 

 piratory system for combinations into superfamily groups 

 of the Physoclysti, and the number of tail vertebrae for the 

 combinations of Physostomi* 



Of these five great divisions he adopted Holocephali 

 from Bonaparte, the Crossopterygii from Huxley, propos- 

 ing on his own part the Actinopteryi or ray-finned fishes. 

 The latter great subdivision which comprises the majority 



* " The greatest defect in this system," says Professor Gill, "was Cope's failure to- 

 emphasize the important distinction between the cartilaginous fishes (Holocephali 

 and Selachii) with no membraneous skeleton, and the Dipnoi. Crossopteri and 

 Actinopteri, which have a specialized system of membrane bones transmitted with 

 more or less modifications to all the higher Vertebrata." 



