xxxvm 



cus) are found in forms on the one hand so closely related (Cyprinodontids 

 vs. Synentognaths) and on the other so much differing from the next ad- 

 joining forms, that the demands of classification appear to be best met by 

 their union in one order. Of that order, the typical physostome fishes are 

 among the most generalized. 



But while the most generalized of the physostome Teleocephals seems to 

 have inherited and retained, in greater measure than any other forms, the 

 primitive characters of the common progenitors of the Teleost fishes, others 

 seem to present claims, but little inferior to theirs, to the rights of primo- 

 geniture. It is, too, quite possible that proofs may yet be produced of the 

 superior rights of such claimants ; it may be demonstrated that on the whole, 

 such present more features in common with the ancient types than those 

 forms to which the rank is now conceded, and that the specialized charac- 

 teristics which now exclude them, are not co-ordinated with other equally 

 specialized characters, and have not the significance they now seem to, but 

 so far as present evidence goes, the claims of the physostome Teleocephals 

 appear to be superior to those of any other forms. 



But from an almost equally generalized stock, and without evidence of 

 very close relationship with any existing or known forms, the Scyphophori 

 and succeeding families seem to have sprung. 



SCYPHOPHORI. 



The Scyphophori appear to be sufficiently differentiated from the phys- 

 tomous Teleocephali by the characters assigned by Cope, as well as other 

 details of the skeleton, and the structure of the brain. On the whole, they 

 appear to be most nearly related among the Teleocephali to the Gymnonoti. 



NEMATOGNATHI. 



The Nematogxathi depart still further from the ordinary Teleocephalous 

 type in the composition of the skull, and especially the union inter se of 

 various elements, as well as in the shoulder girdle, while the peculiar 

 development of the brain confirms the validity of the separation. Their 

 nearest relations appear to be with the Scyphophori. The nearer affinities 

 claimed to exist between them and the Ganoids are not evident, and even 

 the union of the paraglenal eleraeuts is probably the result of coalescence 

 rather than of primitive homogeneity, such as prevails among the Ganoids. 



APODES. 



The Apodes are much diversified among themselves, and have been dis- 

 membered by Prof. Cope into several orders, but they have the same com- 

 mon form and greatly increased number of vertebrae, want of ventrals, 

 simple structure of the rays of the fins, restricted branchial apertures, and 





