71 



TrACHODON (PtEROPELYX) MARC4INATUS. Sp. nOV. 



Plate III, fig. 1, plate IV, figs. 1, 5 and 6, aud plates V, VI, VII, VIII, IX and X. 



Excellently preserved remains, of a large herbivorous dinosaur, met vpith iu abun- 

 dance in the Red Deer river district, are referred to the above species. Although the 

 various bones of the skeleton were generally found distributed, a number were discovered 

 associated with each other, the remains of one individual. These consisted of the hume- 

 rus, ulna and radius of the left fore limb, a metata.rsal and phalanges of the pes, the 

 zygapophyses of cervical vertebrae, ribs, fragments of teeth, broken ossified tendons aud 

 impressions of the integument. The species is represented further by disassociated 

 femora, tibias, metacarpals and phalanges of the manus, rami of the lovs^er jaw and maxillce 

 with remarkably well preserved teeth iu place, dorsal and caudal vertebrce, a pubic bone, 

 ischia, ilia, chevron bones aud numerous teeth as well as other remains probably refer- 

 able to the same species. 



Of the bones, of one individual, found in association, the humerus with the ulna 

 and radius are figured on plates VI and VII. 



The humerus, figs. 1 and 2, has a prominent radial crest that extends, from the external 

 tuberosity above to slightly more than halfway down the shaft externally and is roughly 

 striated at its lower end for the attachment of the deltoid muscle. The head is small and 

 is supported below by a strong rounded ridge. The proximal end, seen from above, is 

 roughly triangular in shape, the front face broadly excavated with conspicuously concave 

 surfaces on either side of the head behind that continue forward to meet the inner and 

 outer tuberosities. The condyles are separated by a deep depression behind, that extends 

 up the shaft for a short distance ; in front they are not so conspicuously divided. 



An archaic feature is expressed in the great downward extension and conspicuous 

 angularity of the radial crest. In comparing this humerus with that of Hadrosaurus 

 FouJkii,* Leidy, from the Cretaceous of the east, a form allied to this species, a marked 

 difference is noticeable in their proportions. 



Measurements cf humerus. 



M. 



Extreme length (27 inches) , • 68.3 



Breadth at lower end of radial crest -165 



Circumference midway between lower end of radial crest and distal end • 265 



Breadth across head and outer tuberosity -140 



" " inner tuberosity -130 



Breadth across inner and outer tuberosities 145 



Breadth of outer condyle • 100 



Breadth of inner condyle (imperfect) • 080 



Thickness at centre of condyles ; ■ 092 



Thickness of radial crest near lower end ■ 034 



*1865. Cretaceous Reptiles of the United States, p. 76, pi. xiv, figs. 1, 2, .3 and 4. Smithsonian Coutr. to Know- 

 ledge, vol. xiv. 



