148 KANSAS UNIVERSITY QUARTERLY. 
which, with its mate, is so prominent 
that it constricts the nasal cavity at 
this place, forming a smaller, secondary 
nasal. cavity behind. This lateral is 
equitrilateral in cross-section, while the 
anterior portion is distinctly quadrilat- 
eral. 
The mandibles have two strong cut- 
ting edges enclosing a deep grove be- 
tween them, the channel for the inner 
ridge of the maxilla. The symphysial 
portion slopes forward at an angle of 
fifteen degrees, and the lower portion of 
the symphysial region extends backward 
Fig. 4—Mandible of Xerobates sg as to cause the otherwise angular 
undata Cope, from above; natural f 
size. symphysis to be broadly concave. 
