Cope.] 



280 



[Oct. 7, 



view I would cite the absence of the maxillary arch in the Dipnoi, and its full 

 development in the Stegocephali, which are the ancestral Batrachia. The 

 large development of the dorsal and anal fins in tlie Dipnoi is not 

 favorable to the Haeckelian view ; nor do the paired fins approach as 

 nearly to the limbs of Batrachia as do those of some other fishes. It has 

 been shown by Huxley tha,t the suspensorium of the Batrachia is hyostylic 

 in its earliest stages, and that it becomes autostylic at a later period ot 

 development. The Batrachia may then have originated from a hyostylic 

 Teleostomous fisli; i. e., one with complete maxillary arch. Among 

 Teleostomata we naturally look for forms with limbs which approach 

 nearest the Batrachian type, and in which median fins are feeble or want- 

 ing. Such are the Rhipidoplerygia, wiiich include the families of Holop- 

 tychiidae, Tristichopteridce, Osteolepididte, Coelacanthidae and perhaps 

 some others. These families, except the last, abounded in the waters of the 

 Devonian period, at the time when the ancestors of the Batrachia also 



Fig. ]. Easlkenopteron foordii Whiteaves; 3^ natural size. Devonian of New Bruns- 

 wick. From Whiteaves. 



existed. All of them agree in possessing the median fins of greatly re- 

 duced proportions, and the mesodermal or internal elements of the paired 

 fins more like the limbs of the Batrachia than are those of any known fishes. 

 The constitution of the superior cranial wall is a good deal like that of the 

 stegocephalous Batrachia. The characters of the fins can be learned from 

 the accompanying figure of tlie Eusthenopteron foordii Whiteaves, one 

 of the Trislichopteridaj. The pectoral fin well-nigh realizes Gegenbaur's 

 theory of the derivation of the Ciiiropterygium from the Archipterygium. 



The question of the ancestry of the Batrachia cannot be considered to 

 be yet settled. 



The ancestral type of fishes is probably tlie Ichthyotomous order of tlie 

 subclass of sharks (Elasmobranchii).* Tliey are hj^ostylic, and have cranial 



*Cope, Proceedings Araer. Philos. Soc, 1S84, p. 585. 



