Stewart.] Cretaceous Fishes, 355 



ened bar with a broad superior surface. This bar is bounded 

 by a well-marked ridge antero-internally, from which the inner 

 wall descends almost vertically. The teeth are not closely set,, 

 the interspaces being occupied by the sockets of the shed teeth ; 

 they are all set on stout bases and are larger than in P. leptogna- 

 thus. These bases vary from round to oval and the apices are 

 about on a level with the external alveolar border. 11 " "The 

 teeth diminish in size from the middle of the dentary bone to 

 the symphysis ; beside the latter are two teeth of reduced size," 

 but on the posterior portion the teeth are but slightly reduced. 

 Just back of the last tooth there is an edentulous portion of 

 about an inch in length, which is followed by a somewhat ele- 

 vated coronoid process. This process is bent outward and cov- 

 ered with irregular longitudinal stria* on the external and 

 internal sides. The lower portion of the bone, below the alveo- 

 lar border, is thin and laminiform, smooth externally, and cov- 

 ered with coarse stria internally. 111 " The symphyseal part of 

 the ramus is not incurved as in P. caninus and P. hingi but is 

 obliquely truncate, indicating that the chin had a compressed 

 form, and was not rounded, as in them." 



Depth of ramus at last tooth 60 mm. 



Diametor of base of tooth 7 " 



I distance from tip of coronoid to last tooth 78 '• 



Number of teeth in one inch, 2.5 to 3. 



Pachyrhizodus caninus. Plate LXX, figs. 3, 4, 5, and G. 



Pachyrhizodus caninus Cope, Proc. Am. Phil. Soc, vol. xn, 1872, pp. 344 

 -346. 



This species is represented by portions of the premaxilla and 

 mandibles of two individuals. There is also a Hat plate of bone 

 accompanying the mandibles whose identity cannot be deter- 

 mine -d. The numbers of the specimens are 145 and 315. 



The teeth on the dentary are supported on a shelf of bone 

 that becomes narrow toward the distal extremity. This por- 

 tion ends abruptly below and is continued into an acute lower 

 border. The jaw is probably shallow throughout its extent, 

 and toward the symphysis the bone is incurved and swollen. 



110. Cret, Vert. West, ;•. 226. 



111. I.e.. p. 225. 



