in the broadly rounded muzzle, in the larger and more posteriorly placed orbits, and in the presence of an intertemporal bone, or at least in the elongate character of the postorbital if the intertemporal is not present. The species on which the genus Eoserpeton is based was first described by Cope as Ceraterpeton ten n iconic. The form is quite distinct, in spite of Jacket's protestations to the contrary. The genus _Stegops_ stands alone among the Carboniferous Amphibia of North America, so far as I am aware, in the possession of a well-defined lacrimal of the labyrinthodont type. =Stegops divaricata Cope.= Cope, Proc. Am. Phil. Soc., XXII, p. 406, 1885 (_Keraterpeton divaricatum_). Moodie, Jour. Geol., XVII, No. 1, p. 79, fig. 22, 1909 (_Stegops_). Type: Specimen No. 2559 G, American Museum of Natural History. The obverse of this is No. 12,311, Walker Museum, University of Chicago. Horizon and locality: Linton, Ohio, Coal Measures. The skull on which this species is based consists of the impressions on two slabs of coal, one belonging to the Newberry Collection of the American Museum of Natural History, No. 2559 G, and the other to the Gurley Collection of the University of Chicago, No. 12,311. The slab belonging to the University of Chicago contains the better-preserved remains, so that the description is based largely on that portion (plate 25, fig. 3). Nearly all of the elements of the skull are determined with considerable certainty and many important characters in the morphology of the Microsauria are thus brought out. [Illustration: Fig. 23.--Skull elements of _Stegops divaricata_ Cope., _fr_, frontal; _it_, intertemporal; _j_, jugal; _la_, lacrimal; _mx_, maxilla; _n_, nasal; _par_, parietal; _pf_, prefrontal; _po_, postorbital; _pof_, postfrontal; _pmx_, premaxilla; _sq_, squamosal; spt, supratemporal; _qj_, quadratojugal; _tab_, tabulare; _pp_, postparietal. × 1.3.] The skull is oval, elongate, truncate behind, and the quadrate angles project into sharp horns. The orbits are elongate ovals and their center lies in the median line which divides the skull transversely. The nostrils are elongate and have an oblique position. The pineal foramen lies in the posterior third of the skull. Teeth are preserved on both maxillæ and premaxillæ. They are simply sharp pleurodont denticles, and seem to have been fairly abundant. The bones have been completely carbonized and nothing of the original texture is preserved, although the details of the structure are beautifully preserved. (Plate 25, fig. 3.)