EXTINCT BATRACHIA. 373 



directed towards the epiotics, which are produced into horns. The pos- 

 terior lateral part of the skull is composed of a broad, shell-like element, 

 probably the squamosal, whose surface is striate, with narrow raised 

 lines. The entire temporal region is roofed in as in other Stegocephali, 

 and the elements are to be identified with postorbital, supratemporal, 

 quadrato-jugal, squamosal, and, perhaps, pterotic. 



The muzzle is short and narrow. The surface of the skull, as indi- 

 cated by a few remains of it, is marked with obscure and irregular 

 ridges. The horns are slender, and directed straight backwards without 

 incurvature. Their surface is finely striate-grooved; the outer face is 

 excavated, and is separated from the superior by a longitudinal angle. 



This species differs very much from the last in its sculpture and in 

 the form of its horns. The specimen described is smaller than that of 

 C. lineopunctatum. 



Length of cranium without horns, .031m.; lengthof ahorn, .012; diam- 

 eter of a horn at base, .0024 ; length of head on middle line, .026; width 

 of head behind, .032; interorbital width, .007 ; length from occiput to or- 

 bits (axial), .0135. 



Ptyonius, Cope (genus novum). 



SauropJeura, part Cope ; Proceed. Ac. N. Sci., Philad., 1868, 217. 

 Oestocephalus, part Cope; Trans. Am. Philos. Soc, XIV., p. 20. 



Form elongate, with long tail and lanceolate cranium. Limbs weak, a 

 posterior pair only discovered. Three pectoral shields present; abdomen 

 protected by packed osseous rods, which are arranged en chevron the 

 angle directed forwards. Neural and hsemal spines of caudal vertebrae 

 expanded and fan-like. Ribs well developed. 



This genus is the most abundantly represented by species and indi- 

 viduals among those found at Linton. These are almost snake-like in 

 their proportions, and vary in length from three to ten inches. The 

 muzzles of the known species are acuminate, and the upper surfaces of 

 the cranium in the three spaces where it is preserved are sculptured by 

 rather distant crests and tubercles. The squamosal is evidently more 

 expanded than in recent Batrachia, either of the tailless or tailed orders. 

 In P. pectinatus and P. Vinchellianus it is a broad plate concealing the 

 quadrate, and apparently readily separable from it, as it is loose in some 

 of the specimens. This is an interesting point, as the homology of the 

 squamosal with the preoperculum of the fishes has been asserted by 

 Parker and the writer,* and the view is confirmed by the resemblance 



* See Proceedings American Ass. Adv. Sci., Vol. XIX., p. 222. 



