Trachodon marginaius (provisioually), whilst the lower oue; 0, Slesrosauroui in its chiiiitcter, 

 may belong to Stereocephalus tutus. 



Fig. 23. — Ilia of herbivorous dinosaurs from Red Deer river ; oiietwelfth the natural size. A, right ilium of 

 Monodonius dau-soni ; B, the same of Tmchodo:i mariiinaliix; C, that oi Sicnoccphahui Iwtuts. A, aeetaljuluni ; P, 

 facet for pubis bone ; Is, facet for iscliiuni. 



Trachodon (Pteropelyx) altidens. Sp. uov. 



Plate IV, figs. 2, 3 and 4. 



A left maxilla, with the teeth preserved, reveals a hitherto undescribcd species of 

 Trachodon. The teeth are distinctly narrow in proportion to their length and are beauti- 

 fully marked, for a short distance above the apex of the crown, on the raised edges of the 

 outer enamelled face by a few, obliquely placed, transversely elongated embossments, 

 which decrease in size gradually, from the apex of the tooth upward until they become 

 inconspicuous as a few marginal denticles or projections. The name of the species is 

 suggested by the height of the teeth relative to their breadth and the distance they 

 project beyond the alveolar border. 



The maxilla indicates an animal of comparatively small size and slender proportions. 

 Three rows of teeth, more generally two, were in use in the grinding surface at the same 

 time, with at least two or three series of successional teeth following, to replace those in 

 use from the inside, the stumps of the old teeth falling out on the outside of the jaw. 

 In fig. 3, the mode of succession of the teeth downward is shown, the bone having been 

 removed for a short distance from the anterior end of the specimen. About one-fifth of 



