352 University Geological Survey of Kansas. 



fragile to be removed from the matrix. The catalogue number 

 of the specimen is 75. 



The dentary is elongated, very slender, and bears eighteen 

 small, conical teeth upon its superior border, each of which is 

 set on a small, bony tubercle of bone, similar to those in P. 

 caninus. The teeth are directed backward and inward, decrease 

 in size from the center toward the extremities, and end pos- 

 teriorly within about an inch of the coronoid process. The 

 symphysis is of a more or less tubercular nature, similar in 

 many respects to that found in P. latimentum, and there are no 

 teeth arranged in a triangle here, as in P. caninus. The external 

 surface of the dentary does not seem to possess any very char- 

 acteristic markings. 



The articular extends forward fully two-thirds the length of 

 the mandible, and is deeply grooved. The cotylus is concave 

 from before backward, and strongly convex laterally. The 

 quadrate is triangular in outline and thin above. Toward the 

 lower portion the bone thickens and assumes a somewhat 

 twisted appearance at the condyle. The condyle is somewhat 

 excavated at the center in order to fit the cotylus. On the in- 

 ternal side there is a well-marked ridge extending from the 

 condyle upward through the center of the bone. The superior 

 border presents a long, narrow sutural surface for uniting this 

 with the metapterygoid. Just back of the quadrate, and articu- 

 lating closely with it, there is a long, narrow element which 

 may be the symplectic. It is covered in part by the preoper- 

 culum, so that its characters cannot be made out. 



The supposed preoperculum consists of a horizontal and a ver- 

 tical portion which meet each other at almost right angles. 

 The horizontal portion possesses no marked characters beyond 

 that it is the broader of the two parts. The vertical portion is 

 broad below, but soon becomes more narrow as the upper ex- 

 tremity is approached. Just back of the anterior border there 

 is a well-defined ridge extending downward to the junction of 

 the two parts. The two flat bones which may represent por- 

 tions of the operculum and suboperculum possess no characters 

 beyond those shown in the figure. 



