Ventral scutellæ are present in one specimen of this species. There are a number of specimens. They have the following numbers at the American Museum: 158, 1100 G, no number, 8341 G (type), no number, 8466 G; and 4477 in the U. S. National Museum. Measurements of Type Specimen of Molgophis brevicostatus Cope. mm. Length of 7 vertebræ 105 Length of 1 centrum 16 Diameter of same vertically 11 Length of a rib on a curve 24 Greatest thickness of same 2.5 =Molgophis wheatleyi Cope.= Cope, Geol. Surv. Ohio, II, pt. II, pp. 369, 370, pl. xlv, fig. 1, 1875. Cope, Trans Am. Phil. Soc., XV, p. 263, 1874. Type: Specimen No. 1101 G, American Museum of Natural History. Horizon and locality: Linton, Ohio, Coal Measures. A critical study of the type specimen of this species does not reveal anything essentially different from the description of Cope. The following is taken from his report (123): "Established on a specimen which exhibits about twenty-five vertebræ with ribs, and the posterior portion of the cranium. No traces of abdominal scales or rods, thoracic shields, or limbs are visible. By such negative characters it is referable to the genus _Molgophis_, although the definition of this genus is incomplete. The present batrachian may, indeed, be ultimately found to be an _Ophiderpeton_, to which it also bears some resemblance. "The specimen is that of an animal of very much smaller size than the _M. macrurus_. The vertebræ are of moderate length, with a low neural spine, and centrum angular at the sides and truncate at the articular extremities when in place. The ribs are rather short, slightly curved, apparently hollow and intercentral in position. Although the vertebral centra are ossified, the elements of the cranium have a larval appearance. These consist of two parallel bony plates, which resemble the fronto-parietal bones of the frog; they are slightly separated from each other, but do not inclose a fontanelle. A wedge-shaped bone extends from the outside of the front of each of these, acuminate behind, and widening anteriorly in the position of a postfrontal bone. In front of the posterior border of each parietal, on its outer side, a bony enlargement arises which contracts outward and forward into a narrow element which curves forward beneath the postfrontal. These look like an anteriorly directed quadrate with articular bone, such as seen in the larvæ and some adults of existing batrachians. These determinations will require confirmation from additional material. In the meantime it is evident that the present specimen can not be referred to any of the other species herein described. The elements of the cranium are entirely smooth with no sign of sculpture, and in this respect the present species is unlike any of the other known from the Carboniferous."