356 University Geological Survey of Kansas. 



The symphyseal surface is of an irregular form, slightly convex, 

 with an emargination entering from the internal side. The 

 jaws were probably loosely united by cartilage at this point. 

 The distal extremity is edentulous, and forms a rather thin 

 coronoid process, coarsely striated internally. There are spaces 

 for from twenty-nine to thirty-two teeth, which decrease in size 

 toward the extremities, and at the symphysis a triangle is 

 formed by three of these. The teeth are rather closely set in 

 places, with enlarged striate bases, while in others the teeth 

 are separated quite a distance from each other where the head 

 crown has not been replaced. The external alveolar wall does 

 not rise as high as in P. leptopsis, mentioned above. 11 ' 2 " The ar- 

 ticular cotylus is composed more largely of the angular than 

 the articular. Its long diameter extends inward and backward, 

 and is strongly convex; in the transverse direction, slightly 

 concave. Below and in front of it the lower margin of the jaw 

 is acute. The angle is oval and rather small ; it is prominent 

 on the middle line on the inner side ; the edges are thin, the 

 upper curved outward, concealing part of the cotylus." 



The premaxilla is elongated, and in the posterior portion of 

 the bone it is narrow transversally. Toward the anterior ex- 

 tremity it becomes much wider and presents alveoli for two 

 large teeth situated internal to the regular series. It is likely 

 that only one of these teeth is functional at a time, as in most 

 of the specimens that I have examined I find only one tooth, 

 and an empty alveolus for the other. The surface for its fellow 

 on the opposite side is roughened by small protuberances of 

 bone. The teeth are slightly larger than those upon the den- 

 tary, but this may be due to the difference in size of the two 

 specimens. There are four preserved on the outer row, but 

 there were probably several more, as Professor Cope describes 

 ten in his specimen. The external surface is finely striated. 



The plate of bone mentioned above shows one surface to be 

 covered with small pits except at the central portion, which is 

 smooth. These pits at first remind one of the empty alveolus 

 on the tooth-bearing elements of Anogmius and some of the 



112. Cert. Vert. West, p. 222. 



