D. Outline of skull and cranial elements of _Erpetosaurus acutirostris_ Moodie, from the Coal Measures of Linton, Ohio. Original in American Museum of Natural History. × 1. _ex_, exoccipital; _fr_, frontal; _j_, jugal; _mx_, maxilla; _n_, nasal; _or_, orbit; _po_, postorbital; _par_, parietal; _pp_, postparietal; _pf_, postfrontal; _sq_, squamosal; _spt_, supratemporal; _tab_, tabulare. E. Outline of larger part of skeleton of _Odonterpeton triangularis_ Moodie, from the Coal Measures of Linton, Ohio. Original in U. S. National Museum. × 4. _h_, humerus; _il_, ilium?; _v_, vertebræ, all of which are not represented. F. Right mandible of _Erpetosaurus tabulatus_ Cope, from the Linton, Ohio, Coal Measures. Original in American Museum of Natural History. × 2. _art_, articular; _cor_, coronoid; _d_, dentary; _ang_, angular; _sa_, surangular. G. Skull elements and lateral-line canals of _Erpetosaurus tabulatus_ Cope, from the Coal Measures of Linton, Ohio. × 1.5. _fr_, frontal; _j_, jugal; _jl_, jugal lateral-line canal; _mx_, maxilla: _n_, nasal; _or_, orbit; _par_, parietal; _po_, postorbital; _pf_, lacrimal or prefrontal; _so_, suborbital lateral-line canal; _pp_, postparietal; _pmx_, premaxilla; _qj_, quadratojugal; _spo_, supraorbital lateral-line canal; _sq_, squamosal; _spt_, supratemporal; _tm_, temporal lateral-line canal; _tab_, tabulare; _so_, supraoccipital cross-commissure of lateral-line canal. ] _Dendrerpeton_ is not well enough known for an exact comparison with _Erpetosaurus obtusus_, but Cope separated the latter from _Dendrerpeton_ on the position of the orbits and the broadly rounded muzzle. This species differs from the other species of the genus in the form of the cranium, as well as in the characters which separate it from _Dendrerpeton_. Measurements of the Type of Erpetosaurus obtusus Cope. mm. Median length of the skull 48 Width of skull at posterior border 56 Width across orbits 37 Length of orbit 12.5 Width of orbit 7 Interorbital space 15 Diameter of nostril 1.5 Diameter of pineal foramen 1.75 Two other specimens, Nos. 8602 G and 8608 G of the American Museum, are associated in this species. =Erpetosaurus tabulatus Cope.= Cope, Proc. Amer. Phil. Soc., XVI, p. 577 (Tuditanus tabulatus). Moodie, Jour. Geol., 17, p. 52, figs. 8, 9, 1909. Moodie, Bull. Amer. Mus. Nat. Hist., XXVI, pp. 347, 351, pl. 59, fig. 2; pl. 62, fig. 2, 1909. Type: Specimen in the Zoological Collection of Columbia University. Horizon and locality: Linton, Ohio, Coal Measures. (Plate 25, fig. 2.)