70 



minntt', obliquely trausverse strife are observed ou the margins of the teeth of T. sehvyni 

 but they are practically smooth, the marginal, or border sculpture characteristic of the 

 teeth of the species described iu the next following 

 pages being absent. 



A few, very large mandibular rami without 

 teeth, one of which is represented in fig. 24, A, are 

 supposed to belong to this species. 



A femur, provisionally associated with T. selwyni, 

 was secured during the summer of 1901. It measu- 

 red about 1-425 M. (56 

 inches) in length when 

 perfect. It is -585 M. 

 and '508 M. in circum- 

 ference above and be 

 low the third trochanter 

 respectively, and indi- 

 cates the size attained 

 by some of the herbivo- 

 rous dinosaurs during 

 Mid-Cretaceous times. 

 For the purpose of com- 

 parison a rediiced figure 



of this immense bone is Fig.-21.-^, front yie« of riglit femur oi Track 



given with a similarly 

 reduced drawing of the 

 femur oilsruarwdon man- 

 telli, Owen, from the 

 "Wealden of Filgate Forest, Siissex, England (see fig. 21). 



odon selwyni, from Red Deer river ; B, front 

 view of right femur of Ignanodon mantdli, 

 from the W'ealden of England One-sixteenth 

 natural size. A, head ; t, great trochanter ; m, 

 third trochanter ; c, inner condyle. 



Fig. 22. — Diagrammatic ro])resenta- 

 tion of the growth of teeth in 

 Traclwdon. A, transverse sec- 

 tion of the mandibular ramus ; 

 B, transverse section of the max- 

 illa. The heavy lines represent 

 the enamelled surfaces of the 

 crowns of the teeth, o, grinding 

 surfaces ; d, much worn teeth ; c, 

 partly worn teeth ; /, successional 

 teeth in the same vertical row 

 witli d and e ; ij, foramen ; h, 

 mandibular groove ; j, inner wall 

 of dental chamber. 



Fig. 22, illustrates, in a diagrammatic manner, the gene- 

 ral mode of succession of teeth in the genus Trachodon. The 

 teeth are represented as they appear in transverse sections of 

 the jaws, the heavy lines indicating the keeled enamelled 

 crowns of the teeth. Thus although in both the upper and 

 lower jaws the teeth replace each other from the inner side, 

 yet the enamelled surface of the crown of the teeth are on 

 the inner side in the lower jaw but on the outer side in the 

 maxilla. 



With this species is connected the name of Dr. Alfred 

 R. C. Selwyn, O.M.G., for many years, prior to 1804, Director 

 of the Geological Survey. 



