The species is known from a single well-preserved skull and its obverse in the collection of Columbia University in New York City. I am indebted to Dr. Bashford Dean for the privilege of studying this interesting form. It is from the Linton deposits of Ohio. The remains include a nearly complete cranium and a complete clavicle of the right side. The species agrees in all essential respects with the characters of the genus _Erpetosaurus_, presenting a broad, flat head and a triangular clavicle. [Illustration: MOODIE PLATE 13 _Dendrerpeton oweni_ Dawson. Above: Skull, mandible, and bones of anterior limbs. Below: Posterior limb, pelvis, and bony scales. Nearly natural size. Erect tree, South Joggins, Coal formation, Nova Scotia. Photograph by Dawson, published through the courtesy of Dr. Arthur Willey. Original specimen in the Peter Redpath Museum of McGill University.] The cranium is wider than long, the muzzle broadly rounded. The orbits are wide ovals, and their posterior borders fall little behind the transverse line dividing the skull equally. The interorbital width equals the long diameter of the orbit. The posterior outline of the cranium is truncate in a straight transverse line between the prominent tabulare angles. The composition of the cranium is different from that of any other species of _Erpetosaurus_ in the large size of the tabulare and the fact that the supratemporal is excluded from the parietal by the extension of the postorbitals and the tabulare. This may be a generic character and entitles the species to be placed in a new genus, but it will be retained here until more of the anatomy of the species is known. The elements of the anterior part of the skull are not preserved, but they are indicated by the broken lines in the drawing (fig. 22, G). The nostrils are, however, clearly indicated as bosses of shale. There is a mere fragment of the nasal preserved posterior to the crack indicated by the transverse line in the drawing. The frontal is elongate as in other species of the genus and forms the inner border of the orbit. The parietal, as usual, is one of the larger bones of the skull roof and the pineal foramen is inclosed in the median suture by the two parietal elements. The pineal opening lies in the posterior half of the parietal. The postparietal is almost square, being slightly elongate transversely, uniting laterally with the tabulare, with which it forms the truncate table of the skull. The suture separating the tabulare from the supratemporal is clearly distinct. Although such a position for the supratemporal is unusual it is not unique, since the same character has been observed in _Diceratosaurus lævis_ Moodie, described elsewhere (p. 120) in this paper. The postfrontal is rather small and it, together with the postorbital, forms the posterior boundary of the orbit. The postorbital is truncate posteriorly and joins the tabulare broadly.