354 University Geological Survey of Kansas. 



The dentary is short and strongly incurved at the symphysis 

 The symphysis is divided by a groove into an external and in- 

 ternal portion. The external is small and tubercular in its 

 nature. The internal is probably the only part that is in con- 

 tact with its fellow on the opposite side, and it has a well-marked 

 ridge extending backward which becomes more indistinct toward 

 the posterior portion . This ridge causes the bone to be thickened 

 just below the alveolar border. The lower portion of the 

 dentary is thin and smooth externally, except on the lower 

 border, where there are short and deep striae extending back- 

 ward. The alveolar border supports probably thirty-eight or 

 forty teeth. These are closely set, non-striated, and directed 

 inward. The external alveolar wall rises considerably above 

 the internal. 



The character of the cotyloid cavity cannot be made out, 

 owing to the quadrate being firmly in place. The outer surface 

 of the articular is covered with striae, which become coarser 

 toward the lower portion. 



The head of the quadrate seems to be broad and bifurcated, 

 as in P. leptognathus . Above the head the bone broadens ante- 

 riorly, and has a strong ridge extending upward along the pos- 

 terior border. Between the jaws v there are several pieces of 

 ossified cartilage covered with minute denticles, somewhat re- 

 sembling shagreen. 



Maxillary: Length from premaxillary surface 135.0 mm. 



Depth of condyle (estimated) 26.0 " 



Mandible : Length from cotyloid cavity 157.0 ' ' 



Length of alveolar border 122.0 " 



Depth at coronoid angle 48.3 " 



Number of teeth in one inch, 8. 

 Hyoid ( ? ) : Distance across anterior end (estimated) 23.0 mm. 



Pachyrhizodus leptopsis. Plate LXX, fig. 1. 



Pachyrhizodus leptopsis Cope, Cret. Vert. West, p. 225, pi. li, figs. 8a, 

 b, and c. 



Represented by a portion of the right dentary bone of one in- 

 dividual and a small portion of the left dentary of another. 

 The number of the specimen is 289. 



The dentary is elongate and the upper portion forms a thick- 



