328 University Geological Survey of Kansas. 



provided with a large pulp cavity. The teeth are largest on the 

 external row, but toward the symphysis they are all reduced to 

 nearly the same size. The symphysis is very shallow. The 

 palatines ( ?) are long and slender plates of bone, which are cov- 

 ered with teeth probably similar in form and size to those found 

 on the dentary. Fortunately the top of the skull is preserved, 

 showing it to be slender, flat, with the different elements arranged 

 very much as in Empo. The vertebras are very similar to those 

 of this genus. 8 " "Their centra in both abdominal and caudal 

 regions are elongate and contracted medially. There is a shal- 

 low longitudinal groove at the bases of the neural and hasmal 

 arches, which are divided vertically by a median rib-like but- 

 tress. The median lateral portion is smooth or nearly so." 

 The known American species are : 



Stratodus apicalis Cope, Niobrara Cretaceous, western Kansas. 

 Stratodus oxypogon Cope, Niobrara Cretaceous, western Kansas. 



Stratodus apicalis. Plate LX; plate LXI, fig. 1. 



Stratodus apicalis Cope, Proc. Am. Phil. Soc. 1872, p. 348; Cret. Vert. 

 West, p. 227. 



This species is represented by portions of the skull and tooth- 

 bearing elements as mentioned above. 



The dentary is elongate and covered with several rows of 

 teeth above and on the internal side. These teeth are largest 

 in the outer row, where they are seven millimeters or more in 

 height, but become very small toward the inner and lower row. 

 The teeth are round in section, acutely pointed, and with 

 slightly recurved crowns. They are entirely without striae even 

 under the microscope. Toward the symphysis the number of 

 rows diminish until only two remain at the extremity, with the 

 exception of three or four small teeth situated external to the 

 outer row. The symphysis is very shallow, in fact, there is only 

 a small articular facet at this point, which shows that the jaws 

 were very loosely united here. Throughout its whole length 

 the dentary is very shallow and covered with coarse longitudinal 

 striae on the external side. Unfortunately the articular portion 

 is not preserved. 



86. Proc. Am. Phil. Soc. 1878, p. 181. 



