Cope, Geol. Survey Ohio, II, pt. II, 380, 1875.
Type: Œstocephalus remex Cope.
Form slender and snake-like; caudal vertebræ with elongated, dilated, sculptured neural and hæmal spines. Cranium lanceolate. Teeth numerous, of nearly equal size. No pectoral shields known; abdomen protected by very numerous bristle-like rods, which converge forwards. A pair of weak posterior limbs; branchihyal bones present.
In the only well-preserved species the cranial bones exhibit no sculpture from the parietal region forward. The genus is not very distinct from Ptyonius, but it can not be united with that genus until more complete material is available. The species of the genus share with Ceraterpeton, Urocordylus ([334]), and Ptyonius, as well as Crossotelos ([98]), from the Permian of Oklahoma, the elongation, sculpture, and expansion of the neural and hæmal spines. There are but 2 species, which Cope distinguishes by the following characters:
I. Vertebræ elongate; fan-like caudal processes narrowed. Size large; mandibular teeth of unequal lengths, with the apices turned backward Œstocephalus remex
II. Species only known from cranial bones with teeth. Teeth equal, erect, with acute conic apices, 11 in 5 mm Œstocephalus rectidens
Œstocephalus remex Cope.
Cope, Proc. Phila. Acad. Nat. Sci., p. 217, 1868 (Sauropleura remex).
Cope, Proc. Phila. Acad. Nat. Sci., p. 218, 1868 (Œstocephalus amphiumianus).
Cope, Trans. Amer. Phil. Soc., XIV, p. 17.