SYSTEMATIC REVISION 53 



There is considerable resemblance between several parts of this animal and 

 those of the stegocephalian Batrachia. This is seen in the forms of the femur 

 and the shoulder girdle, which are similar to those which I have referred 

 to Eryops. The close approximation of the huge auricular meatus to the 

 orbit is only seen elsewhere in the anourous Batrachia. The teeth on the 

 other hand are of strictly reptilian type in their mode of implantation, and 

 the lack of dentinal inflections distinguishes them from those of many of the 

 genera of Stegocephalia. There is nothing in the shoulder girdle to distin- 

 guish it from the Cotylosauria, and the humerus so far as preserved is of the 

 type of that order. It is impossible to get at the occipital condyles without 

 destroying important parts of the specimen. The vertebrae are amphicoelous. 



"It is probable that in life the species of this genus had an enormous 

 tympanic drum. 



"The tabular part of the skull is large as compared with the facial 

 part. The posterior border is broken in the 0. testudineus, but it is con- 

 tinued to a transverse line posterior to the auditory meatus. It was not 

 probably produced into a horn-like process. The suspensorial part of the 

 quadrate is directed posteriorly below. The mandibular ramus has a hori- 

 zontal expansion of the inner side just anterior to the short angle. 



"The clavicles have the distal expansion overlapping the episternum 

 characteristic of the order. The shaft makes an obtuse angle with the 

 expanded portion, and is compressed. Its proximal extremity is expanded 

 into a rounded disk, whose plane is horizontal and at right angles to that 

 of the shaft. Between the shaft and the mandibular angle the edge of the 

 pterygoid is visible. The episternum has the posterior part broken off. The 

 part preserved is a transverse plate, which has, like the clavicles, a smooth 

 surface. The scapula lacks the proximal end. Distally it presents a strong 

 longitudinal ridge which extends to the coracoid. Anteriorly the shaft 

 expands into a procoracoid laminar extension in its plane. The coracoid is 

 small and has a convex internal border, which is not notched as in the Pely- 

 cosauria. It may be coossified with the scapula. The humerus has a greatly 

 expanded head and a narrow shaft. 



"The femur is longer than the tibia, and displays the condyles charac- 

 teristic of the Cotylosauria and Pelycosauria. They are unequally produced 

 posteriorly. There is a long and strong anterior crest. 



"Two vertebral centra are only moderately well preserved. They are 

 probably anterior dorsals. They are wider than long and are separated by 

 a large and protuberant intercentrum. A free intercentrum of the same 

 shape lies at one side. It is probable that a rather short neural spine rises 

 to the inferior side of the carapace. Only the part next the carapace can be 

 seen in the specimen. 



"The ribs are much expanded, but do not touch each other. The cara- 

 pacial bands alternate with them above, resting on their adjacent edges and 

 separated by narrow interspaces. Towards the supposed anterior part, the 

 superior costal surfaces rise between the carapacial bands to the plane of 

 the latter, forming a closer surface than posteriorly. 



"This genus forms a remarkable example of homoplastic resemblance 

 to the rhachitomous genus Dissorkophus, which I described in the 'American 

 Naturalist' for November 1895. The superficial resemblance is very great, 

 and it is only after an examination of the constitution of the carapace that 

 the difference of this part of the structure in the two genera is observed. 



