"The lower portion of the dentary is prolonged into an acute angle. This is separated by a deep and wide concavity from the superior posterior prolongation, which is obtuse, and rises at once into the coronoid process. Teeth on this dentary, seven; the same number is on the preserved ramus; this number is suspected to be complete, or nearly so. The teeth terminate at the obvious termination of each ramus, which is, it is true, slightly obscured. These teeth are the longest in the Microsauria in relation to the depth of the ramus, equaling the largest in _Œstocephalus_. They are doubtless exposed, as are some of those of the last-named genus, by the splitting away of the outer parapet of the dentary bone. As no traces of alveoli have been thus rendered visible I suspect the dentition to have been acrodont, as in some existing Batrachia. "No external surface of the mandible remains, but there are no impressions of sculpture on the matrix. A little external face of the premaxillary displays none. "The species is dedicated to Professor John S. Newberry, the able director of the Geological Survey of Ohio, and discoverer of most of the Batrachia herein described." Measurements of the Type. mm. Length of ramus of mandible (imperfect) 22 Depth at last tooth 5 Length of exposed tooth 3.5 Length of dentary 16 Depth at coronoid process 7.5 Depth at first tooth 3 =Genus PROTERPETON new genus.= Type: _Proterpeton gurleyi_ Moodie. Known from a single vertebra. Spine very high and heavy, the neural canal large. =Proterpeton gurleyi new species.= Type: Specimen No. 13,296, Walker Museum, University of Chicago. Horizon and locality: Coal Measures near Danville, Illinois. The vertebra, as preserved, is well characterized by the figure (plate 22, fig. 2). The spine is high and heavy, the neural canal is large, and the centrum reduced. The form is very unusual. It is apparently from the cervical region, as there are no indications of zygapophyses, transverse processes, or hæmal arches, although they may have been abraded; apparently not, however. The type specimen was discovered near Danville, Illinois, about the horizon of the Danville coal, so that it is quite high in the Allegheny series of the Pennsylvanian and of about the same horizon as the phalangeal bone from Breeze, Illinois, which may be provisionally associated with this form. There is no assurance that Proterpeton gurleyi is an amphibian. The vertebra may have belonged to a fish. Measurements of the Type of Proterpeton gurleyi Moodie.