The specimen represents the left side of the face, and the characters exhibited by the fragment are supported by more complete material (No. 2933, Am. Mus. Nat. Hist.). The skull shows a close approach to the higher labyrinthodonts in its shape. The orbits are far removed from the border of the skull. The arrangement of the bones of the skull resembles that of _Capitosaurus_ from the Keuper of Europe. The jaw is for the most part slender, with a pronounced downward inflection at the coronoidal part. The teeth are heavy and strong and are curved backwards. They have the strong longitudinal fluting which is characteristic of the labyrinthodonts. Another character which is distinctive is the pattern of cranial sculpture. This consists of inosculating pits and grooves of a coarse character and compares favorably with the sculpturing of Triassic labyrinthodonts. If _Macrerpeton_ really represents a labyrinthodont form of Amphibia it is the oldest of the known Labyrinthodontidæ, since it seems probable that the _Eosaurus_ vertebræ came from a higher horizon. =Macrerpeton huxleyi Cope, 1874.= Cope, Trans. Am. Phil. Soc., XV, p. 274, 1874. Cope, Geol. Surv. Ohio, II, pt. II, p. 397, pl. xxxiv, fig. 2, 1875. Lesley, Dictionary of Fossils, p. 1237, 1890. Moodie, Jour. Geol., XVII, No. 1, p. 72, fig. 17, 1909. Moodie, Bull. Am. Mus. Nat. Hist., XXVI, art. XXV, p. 354, pl. lix, fig. 1, 1909. Type: Specimen No. 119, American Museum of Natural History. Collection of Dr. J. S. Newberry. (Plate 26, fig. 2.) Horizon and locality: Linton, Ohio, Coal Measures. [Illustration: MOODIE PLATE 26 1. Photograph of type specimen of _Erpetosaurus tuberculatus_ Moodie, from the Ohio Coal Measures. × 1. Original in American Museum of Natural History. 2. Photograph of type of _Macrerpeton huxleyi_ Cope, from the Ohio Coal Measures. × 1. Original in American Museum of Natural History. ] The first part of the following account of the species, _Macrerpeton huxleyi_ Cope, is a quotation of Cope's description (123) of the type specimen, and the second part deals with the description of the new material. Cope says the species is "Represented by a considerable portion of the face and muzzle of a single individual. A portion of the left mandible, supporting three teeth, remains in place, and almost the entire boundary of the right orbit is preserved. "The fragment indicates a much larger species than any other referred to the genus, and, next to the _Leptophractus obsoletus_, the largest of the Batrachians of the Ohio Coal Measures. Without more complete remains, it is not easy to determine its generic relations finally.