252 



PROCEEDINGS OF THE NATIONAL MV8EVM. vol. xxxvi. 



National Museum also show but eight. It appears that the number 

 will vary in fully adult individuals, due to the fusion of the smaller 

 with the larger members. 



The proximal row forms two distinct concave surfaces for articu- 

 lation with the distal ends of the radius and ulna. These articulating 

 surfaces are clearly defined, as in many of the fore limbs of the 

 mammalia, an unusual condition as is well known to all who have 

 attempted to articulate the limb and foot elements of most members 

 of the Dinosauria. The contour of these opposing articular ends is 

 distinctly shown in fig. 27. which represents the right fore foot of C. 

 browni, and is reproduced from a photograph of the specimen as it 

 was found in the quarry. 



The radiale (r)is an irregularly shaped, block-like bone, the most 

 iTv robust element of the carpus. Its 



nvC- 1 



proximal end forms the chief sup- 

 port for the radius, the distal end 

 articulates with Metacarpal I and 

 carpalia one, two, and three, and 

 externally with the internal bor- 

 der of the intermedium, with 

 which it is often coossified (see 

 fig. 27). The union Avith Meta- 

 carpal I is at an angle of nearly 

 45° to the main axis of the foot, 

 and in all of the feet studied, 

 where these elements were pre- 

 served, they were found to be 

 firmly ankjdosed, particularly 

 along the anterior surfaces, as 

 will be seen in fig. 28. This digit 

 was thereby rendered immovable, 

 which is suggestive of the " spike-like '' digit of the allied Iguanodon. 

 The intermedium (in) viewed from the front is subtriangular in 

 outline, the apex pointing toward the lilnare (see in, fig. 28.) Its 

 dorsal surface articulates with both the radius and ulna, but more 

 especially with the latter; ventrally it is supported by Metacarpal 

 III, and a small, irregularly shaped element on the posterior internal 

 part of this end which probably represents C.j. Although apparently 

 in position in this foot, in the right fore foot of another specimen 

 (Cat. Xo. 5473, U.S.N.M.), C3 lies more over the proximal eud of 

 Metacarpal III, which somewhat confirms its identification. This 

 element, however, is about equally divided between the intermedium 

 and radiale. 



The ulnare (n) is a cushion-like bone, its transverse being greater 

 than tlie antero-posterior diameter (see u, figs. 27 and 28). It has a 



Fig. 28. — Right foue foot, Camptosaurcs 

 DisPAR Marsh. Cat. No. 4277, U.S.N.M. ; 

 i NAT. SIZE. Seen fro.m the front. 

 C-, carpal two ; c*, carpal four ; c^, 

 carpal five; in, intermedium; mc I, 

 metacarpal I ; r, radiale ; u, ulnare ; 

 I TO V, digits one to fivf. Ungual 

 of first digit restored. 



