This specimen is of interest in respect to the presence of the lateral-line canals, its small size, and its generic identity with forms from Ohio. There is still another form known from the Cannelton slates, described below as _Erpetosaurus (Tuditanus) sculptilis_ Moodie. Measurements of the Type of Erpetosaurus minutus Moodie. mm. Length of skull 18 Posterior width of skull 17 Width of skull across orbits 14 Length of orbit 4.5 Width of orbit 3.5 Interorbital width 3.5 =Erpetosaurus sculptilis Moodie.= Moodie, Jour. Geol., 17, No. 1, p. 61, figs. 11, 12, 1909 (_Tuditanus sculptilis_). Moodie, Bull. Am. Mus. Nat. Hist., XXVI, p. 347, 1909 (_Erpetosaurus sculptilis_). Moodie, Proc. U. S. Nat. Mus., 37, p. 22, 1909 (describes pectoral girdle). Type: Specimen No. 12,315, University of Chicago, Walker Museum. Horizon and locality: Cannelton slates, Pennsylvania (Upper Freeport). (Plate 18.) There is preserved in the collections of Walker Museum of the University of Chicago a small amphibian skull pressed flat on a slab of slate from Cannelton, Pennsylvania. It formed part of the Hall collection acquired by the University of Chicago in 1908. The specimen presents only a portion of the skull and fragmentary pectoral plates. The skull is wider than long and the muzzle is broadly rounded. The orbits are narrow ovals and their posterior border falls on the transverse line dividing the skull equally. The interorbital width is slightly greater than the width of the orbits and about equal to their length. The posterior outline of the skull is somewhat truncate, as in _E. tabulatus_ Cope and other species of the genus. The distal extremities of the quadrates do not project as far backward as do the supraoccipitals. The skull roof is formed of the regular elements, except that a quadrate seems to be indicated by a scale of bone on the posterior angle. The nostrils are oval and the pineal opening is small.