408 GEOLOGICAL SURVEY OF THE TERRITORIES. 



of the arch for this prominence are marked. The neural spine had a 

 strong anterior ala, the base of which extends to the summit of the 

 neural arch. It presents a fine striation vertical to the centrum and 

 oblique to the edge of the bone, as is seen in C. propython, Cope. The 

 diapophysis on this vertebra looks obliquely upward and carries a ver- 

 tical articular surface which is concave behind. The line of its lower 

 extremity falls the depth of the neural arch below the latter, and of its 

 upper to the apex of the canal in front. The more posterior vertebra 

 has as usual a broader articular rib surface, the diapophysis being flat- 

 tened above and below. The marginal and angular surfaces are striate- 

 rugose on these and the other vertebras. One of the free hypapophy- 

 ses of a cervical is preserved. It has a subtrigonal section, and is 

 longer than wide, and obtuse. Its posterior faces are exceedingly rugose. 



A cervical rib is compressed and short. Head narrow, long, simple, 

 the adjacent sides striate-rugose. Sides with a shallow groove. 



The scapular arch is represented by an entire right scapula and prox- 

 imal part of right coracoicl. The former is broader than in any of the 

 species in which I have seen it (four only) and is flat, and above, thin. 

 Its anterior extension is greatest below, its posterior above, at the supe- 

 rior angle. The lower posterior margin is strongly concave and thick- 

 ened. The antero-superior margin is a regularly convex arc of more 

 than 180°. The lower portion in front is on a different plane and is the 

 rudimental acromion. The articular surface with the scapula is rugose, 

 and the glenoid cavity not less so. 



The proximal portion of the coracoid is flat. It presents the usual 

 foramen near the anterior margin, and the shorter concavity of the an- 

 terior margin leads to the belief that the anterior extremity of the bone 

 is the more prolonged, as in Clidastes propython. 



The glenoid cavity is not concave, but merely two adjacent flattened 

 rugose surfaces. 



Consequently, the humerus has no head, but merely an elongate artic- 

 ular surface, which exhibits a median keel and a short, angular expan- 

 sion near the middle. This bone is of remarkable form, more resembling 

 that I have described in Clidastes propython* than any other, and very 

 different from that described by Leidy in Platecarpus tympaniticus. It 

 is a broad, flat bone, expanded at the extremities in one plane, distally, 

 so as to be as wide as long. In the present individual it is crushed by 

 pressure, so that its thickness is not readily determinable. Its external 

 surface rises into a crest medially at the narrowest portion, which con- 

 tinues to the lateral angle of the proximal end, following parallel to one 

 of the borders. A moderate thickening exists on the opposite side, a 

 little beyond the extremity of the crest. Strongly rugose strise extend 

 to the edges of the articular faces. An oval rugose muscular insertion 

 exists on the least prominent of the distal angles, and not on a pro- 

 cess, as in G. propython. 



A bone which, from its analogy to the radius of the last-named species, 

 I suppose to be that bone, accompanies the others. It is flat, truncate 

 proximally, and with nearly parallel borders on the proximal half. 

 Distally it is obliquely expanded, the outline forming a segment of an 

 ellipse whose axis is oblique to that of the bone. Its extremities are 

 rugose striate. 



One carpal remains ; it is a quinquelateral bone, one side being mar- 

 ginal and concave. Perhaps it is the intermedial. There are several 

 elements which are probably metacarpals. The general structure of the 



* See Trans. Amer. Philos. Soc, 1869, 219, Tab. XII, Fig. 17. 



