158 Prof. E. D. Cope on the Systematic Relations of Fishes. 



and malar. In the other genera the relations of the maxillary 

 are as in osseous fishes. 



The Stm-geons (Acipenseridse) agree with Amia &c. in all 

 of these points but one, differing only in having the superior 

 cerato-hyal and several of the superior branehio-hyals cartila- 

 ginous. The one point of distinction is the extension of the 

 basal radial supports of the ventral fin all across its basis, as 

 in Polypterus. The pectoral fin is, on the other hand, much 

 as in Lepidosteus. Thus the Sturgeons combine in this one 

 respect the features of both divisions. Both the basal cerato- 

 hyals are cartilaginous in this family ; the superior only is 

 cartilaginous in Polypterus., Lejndosteus^ and Amia ; while 

 both are ossified in the old Teleostei, except in the Eels. In 

 these the inferior is cartilaginous, while the superior is co- 

 ossified to the cerato-hyal. Thus in one unimportant character 

 Polypterus agrees with its former associates, but differs more 

 from others of them (the Sturgeons) than from the bony fishes. 



Another character of both Lepidosteus and Amia betokens 

 a certain relationship to Polypterus.^ viz. the complexity of 

 the mandible, especially in the possession of a coronoid bone. 

 But here, again, Acipenser only possesses an osseous dentary, 

 while Oymnarchus and Gymnotus have the angular and arti- 

 cular bones distinct from the dentary, wanting the coronoid 

 and opercular. In most bony fishes the angular is not distinct. 



It is thus evident that the subclass Ganoidei cannot be 

 maintained. It cannot be even regarded as an order, since I 

 Avill show that Lepidosteus., Acipenser., and Amia are all re- 

 presentatives of distinct orders. I hope also to make it evident 

 that Polypterus should be elevated to the rank of a subclass or 

 division of equal rank with the rest of the fishes and with the 

 Dipnoi already adopted. 



The question may be discussed as to Avhether naturalists 

 are correct who regard the fishes as representing, variously, 

 from two to four classes. One of these (the Ganoidei) having 

 been already disposed of, it remains to consider the claims of 

 the remainder, viz. the Elasmobranchii (Sharks), Dipnoi, and 

 typical fishes. 



If we examine the points in which the whole taken together 

 differ from the Batrachia and other classes above it,we find that 

 these are confined chiefly to the structure of the limbs and the 

 liyoid apparatus. The typical fishes present, however, other 

 important peculiarities, viz. : — 1, the existence of two or three 

 distinct bones in the suspensor of the mandible, instead of 

 one ; 2, the attachment to these of the opercular bones ; 3, the 

 absence of pelvic bones ; 4, the suspension of the scapular 

 arch to the cranium ; 5, the large development of the pterotic 



