"Stewart.] ( 'retaceous Fishes. 351 



well defined. Its anterior part has a massive transverse eleva- 

 tion, which sends a short median process backward, producing 

 a T-shaped body ; the frontal suture is probably in front of 

 this. The supraoccipital is contracted behind this body, and 

 its postero-exterior suture presents a remarkable peculiarity in 

 a straight and wide truncate articular face. This is opposed 

 by a corresponding face of the parietal bone. The latter is of 

 an irregular form, and carries on its outer portion next the 

 pterotic a stout protuberance. This is at the inner end of a 

 •strong ridge, which disappears near the outer edge of the 

 pterotic. The protuberance looks as though adapted for an 

 articulation. The frontals send a process backward, between 

 the ' supraoccipital ' and the pterotic or postfrontal, to the base 

 of the tuberosity of the parietal. The suture between the 

 exoccipital and parietal is not clear. A suture is distinct 

 enough, bounding the latter behind, but whether an expansion 

 of the supraoccipital intervenes or not is not certain. The ex- 

 occipitals appear to be fiat and quadrant-shaped, having convex 

 antero-lateral borders. Each bears a strong condjde." 



The vertebrae present no deep lateral grooves, but are longi- 

 tudinally stria red and rather elongated back of the cervical 

 region. 



The following species have been described from Kansas : 



Pachyrhizodus kingi Cope, Niobrara Cretaceous, western Kansas. 

 Pachyrhizodus latimentum Cope, Niobrara Cretaceous, western Kansas. 

 Pachyrhizodus sheare.ri Cope, Niobrara Cretaceous, western Kansas. 

 Pachyrhizodus caninus Cope, Niobrara Cretaceous, western Kansas. 

 Ptichyrhizodus leptopsis Cope, Niobrara Cretaceous, western Kansas. 

 Pachyrh 'zodua leptognathua Stewart, Niobrara Cretaceous, western Kansas. 

 Ptichyrhizodus ve/ox Stewart, Niobrara Cretaceous, western Kansas. 

 Pachyrhizodus minimus Stewart, Niobrara Cretaceous, western Kansas. 



Pachyrhizodus leptognathus. Plate LXTX, fig. 1. 



Pachyrhizodus leptognathus Stewart, Kans. Univ. Quart., vol. vn, p. 103. 



This species is represented by the left mandible, quadrate, 

 s}*raolectic, preoperculum, and two broad, flat plates of bone, 

 which are probably the operculum and suboperculum. With 

 the exception of the anterior portion of the dentary, only the 

 internal sides of the bones can be examined, as they are too 



