Ptyo. 



842 





tope: 



?cd, 

 Ohio, 



Voin, 



186S, 217) and Oestocephalus (Trans. Am. Philos. Soc. Phila 

 XIV, p. 20) were re named Ptyonius (Trans. A. F. S. April, 

 1874) ; are the most fish -like of the ancient frogs ; with num- 

 erous small, both simple and grooved teeth, extending in one 

 species at least to the tips of the slender jaws ; and with a head 

 which is a curious miniature of the later Ichthyosaurus. 

 Compare the Irish genus Lepterpeton^ Huxley; and Urocor- 

 dalys, Huxley. In the figure the three thoracic shields have 

 been displaced ; no teeth preserved ; nothir g like limbs shown ; 

 back armour consists of long, narrow sub-cylindrical scales, 

 diverging from the middle line (as in the long rod-like pieces 

 or Oestocephalus >) XI IL 



Ptyonius nummifer, Cope, Pal. Ohio, Vol. 2, 1875, page 



X(IL 



Cope. 



Ftctte XL . 



374, plate 40, fig. 2, 3, both natural size. Two specimens of 

 this reptile are described by Cope (p. 374, 375.) One shows 

 well developed tail fans; breast shields of a peculiar form (no 

 side shields visible) sculptured in strong ridges; a head differ- 

 ent from and wider than that of the other four known species; 



