PERMO-CARBONIFEROUS VERTEBRATES FROM NEW MEXICO. 



23 



the distal end of the ulna, forms a notch into which the intermedium fitted, and 

 a larger outer face, nearly horizontal and occupying most of the distal end. 



The carpus: In no specimens of the Diadectidae previously collected have 

 more than a few of the bones of the carpus been preserved and in none are they 

 in position. In this specimen most, if not all, of the carpal elements of the right 

 side are in connection with the radius and ulna and some of the metacarpal bones, 

 though somewhat disturbed by the bending of the foot backward and inward. 

 The carpus of the left side is separated from the bones of the fore-arm and not all 

 are preserved. Seven bones are clearly preserved on the right side and there are 

 indications of two others. The bones of the proximal row and a centrale are large 

 and well formed, but those of the distal row are reduced to small nodules and were 



Fig. II. — Diasparactus zenos Case, X yi. A, anterior view of left ulna; B, inner view of left ulna; C, ante- 

 rior view of left radius; D, upper end of left radius; E, lower end of left radius; F, lower ends of right 

 radius and ulna with carpals of proximal row, upper surface ; G, carpals of distal row of right side with 

 attached metacarpals, upper surface. This is the distal portion of the carpus shown in F, which is bent 

 back upon itself; H, metacarpal and phalanges of third digit of right front foot. 



evidently inclosed in a considerable amount of cartilage, resembling in this respect 

 the foot of Limnoscelis, described by Williston.* The ulnar e is roughly oval in 

 shape, with broad articular faces for the intermedium, the ulna, and carpale IV. 

 The outer edge is narrowed above, but widens below to form a triangular articular 

 surface which probably afforded attachment to a pisiform, which is not preserved, 

 however, in either carpus. The intermedium is thick and oval in outline; it articu- 

 lated fairly closely in the notch formed by the adjacent faces of the radius and 

 ulna, and touched the radiale, ulnare, and the centrale. The radiale is smaller, 

 rather longer than wide, and lay along the larger, inner, facet of the radius. As 

 in Limnoscelis, it was not large enough to articulate with this face for its whole 

 length. The centrale is elongate with a fiat lower face; the upper face is fiat on the 

 radial side, but near the ulnar end there is a sharp upward projection which fitted 

 between the ulnare and the intermedium. On the radial end of this bone there is 

 a small fragment partly inclosed in matrix which may indicate the second carpale. 

 The bones of the distal row are all small and of indefinite form. One, of larger 

 size, probably carpale IV, lies below the ulnare, a second below the ulnar end of 



* Am. Jnl. Sc, vol. xxxi, May 191 1, p. 390. 



