77 



the maxilla is missing anteriorly, as well as a considerable part of the superior border 

 above the row of foramina. A prominent, overhanging ridge, runs forward, on the 

 outer side, from the posterior end, forming the outer and lower border of the facet for the 

 front part of the jugal. A noticeable feature is the distance the teeth project beyond the 

 borders of the alveolar walls. Four neuro-vascular foramina are conspicuous in the outer 

 wall in front of the ridge just mentioned. The enamelled surface of the crown of each 

 tooth bears a strong median carination. The teeth from which the apices have been 

 removed by use are quite smooth and do not show the characteristic border markings. 



COMPARATIVE TABLE OF TEETH OF SPECIES OF TRACHODON AND PTEROPELYX. 



Trachodon mirabilis, Leidy. 



Teeth pointed above ; margins smooth. 



Traehodon (^Fterojielyx) sdtvyni, Lambe. 



Teeth rounded oval above ; margins smooth or with 

 the faintest indications of oblique transverse 

 striiB. Fig. 2, plate III. 



Trachodon (Pteropelyx) marijinalus, Lam be. 



Teeth rounded above ; with a marginal sculpture. 

 Figs. 5 and 6, plate IV. 



Pleropelyx grallipes, Cope. 



Teeth rounded above ; with a border sculpture. 

 Fig. 7, plate IV. 



Trachodon (Pteropelyx) altidens, Lambe. 



Teeth of small size, long in proportion to the breadth, 

 and pointed above ; with a border sculpture near 

 the apex. Fig. 4, plate IV, 



