PALEOZOIC TIME CARBONIC. 



687 



The Fishes were of Coal-measure types of Ganoids and Selachians. The 

 genera of the former included Ctenodus, Ptyonodus, and others ; also Cerato- 

 dus, a Dipnoan genus, which here has its first known species, while its last is 

 still living in Australia ; the Permian, C. favosus of Cope, is from Texas. 

 Sharks occurred of the genus Diplodus, and along with them spines of Ortha- 

 cantJius, which have been shown to have belonged to Diplodus, as suggested 

 by Dawson in 1869 from the association of specimens in the Pictou coal- 

 field, Nova Scotia. 



The Amphibians were, like the earlier, mostly Stegocephs. Fig. 1123 of 

 the cranium of Eryops megacephalus of Cope, from Texas, shows that the 

 head had the tvell-roofed character to which the name Stegoceph alludes ; 

 and the length of the cranium, over 22 inches, indicates a large species. 

 Two long, narrow-headed species, Cricotus heteroditus (Fig. 1124) and C. 



1124. 



Amphibian. — Cricotus heteroclitus (x |). Cope. 



Gibsoni Cope, have been found in the Permian of Danville, eastern Illinois, 

 and the former also in northern Texas. 



The Permian Reptiles, the earliest of the class, belong to the tribe 

 Bhynchocephalia, which, like the genus Ceratodus among Fishes, is nearly 

 extinct. Only two species, of the genus Sphenodon (or Hatteria), now exist, 

 and these are confined to New Zealand — a piece, like New Guinea, of a now 

 half-extinct continent, Australia. One of the earliest of the species is proba- 

 bly the Mesosaurus {Stereosternum) tumidus of Cope (Fig. 1125), from beds 

 containing shells of Schizodus in the Permo-Carboniferous of Sao Paolo, 

 Brazil. It may be, however, from a bed below the Permian. Cope mentions 

 its relations to the Amphibians and closer to the Ehynchocephalian Reptiles, 

 and the interesting fact, of primitive aspect, that the foot, as the figure shows, 

 has a tarsal bone (1 to 5 in figure) to each of the five metatarsals (I to V), 

 five in all, or the normal number, instead of four, which is the largest number 

 in later Eeptiles. 



Other Permian reptiles, but probably later stratigraphically, are those 

 of Clepsydrops of Cope, three from Texas and as many from Illinois ; of 



