350 University Geological Survey of Kansas. 



of succession, as described by Professor Cope, is as follows: 107 

 "The crown of the young tooth was developed in a capsule at 

 the base of the crown, or on the inner side of the apex of the 

 thick root. The absorption which followed excavated both the 

 former and the latter; but the crown was evidently first shed. 

 Finally the old root disappeared and the new one occupied the 

 alveolus, leaving a free separation all round. Finally, on the 

 accomplishment of the full growth of the root, it became an- 

 chylosed all round." The articular portion of the mandible 

 does not seem to be formed of the derm and antarticulars, as in 

 Saurodon, etc. 



The prem axillae are much more elongated and of an entirely 

 different form from those of the Stratodontidx . They bear a 

 single series of teeth on the external side and two more larger 

 ones internal to the regular series. The maxillae are rather 

 shallow and are not united with the palatine, as in the Ichthyo- 

 dectidds and Saurodontidve mentioned above. There are several 

 other elements covered with villiform teeth whose position is 

 not known. 



There is no complete skull preserved in the museum, but 

 Professor Cope says: 108 "The cranium is flat and wide, and 

 pressure has probably somewhat increased the effect in this 

 instance. Exoccipital, supraoccipital, epiotic, pterotic, parietal 

 and frontal bones are clearly distinguishable, but there are 

 points where the sutures are obscure. The best defined are the 

 epiotics, which are subtriangular bones presenting the apex 

 inward and bearing a small round facet for the supratemporal 

 on the posterior angle. The pterotics and postfrontals may be 

 easily distinguished from adjoining bones, but not so well from 

 each other. They have a thin outer margin, and their superior 

 surface is marked by bands of irregular small fossae and an 

 obtuse longitudinal ridge. The middle line of the skull is 

 occupied by the supraoccipital. Its proximal portion probably 

 separates the exoccipitals, but this is not certain. It extends 

 well forward, and the line of separation from the frontal is not 



107. Cret. Vert. West, p. 220. 



108. 1. c, pp. 220a, 220b. 



