622 



WILLIAM R. SMELLIE ON 



with intermedium and ulnare (uln.). The third bone articulating with the humerus 

 is the pisiform {p.), which is a hexagonal platelet of bone fused to the ulna. The 

 posterior margin of the pisiform is thin and evidently a finished edge of bone ; but 

 between this and the humeral facet there is a facet, for the accommodation of a 

 definite ossicle (a.), similar in size to the facet on the post-axial margin of the distal 

 expansion of the humerus. Although the fourth bone (a.) is missing, the excellent 

 preservation of the other bones shows the facets above mentioned with such precision 

 that there is little risk in postulating the presence, position, shape, and size of this 

 accessory ossicle (a.). The presence of this bone completes the resemblance of this 

 part of the paddle to Tricleidus (text-fig. 8, A, a.). The proximal row of carpals 

 consists of the radiate (rad.), carrying a fused accessory ossicle and articulating with 

 a second ; the intermedium (int.); and the uhiare (uln.), which articulated with an 



TuxT-Fifi. 9. 

 Diagrammatic restoration of the skeleton of Apractodeidus teretipcs. (About ^ e th nat. size.) 



accessory ossicle occupying the angle contained by the posterior margins of the 

 pisiform and ulnare. The three distal carpals are similar in shape to the bones in the 

 proximal row, but smaller in size. The shape and articulations of the carpals and the 

 close-fitting pavement they form are best described by reference to the plate and 

 figure (Plate, fig. 4 ; text-fig. 8, B). The fourth bone, in the same row as the 

 distal carpals, is the fifth metacarpal (B, mc.V.). This bone is somewhat flattened, 

 like the carpals, and articulates with the ulnare and the third distal carpal, but 

 otherwise it shows a tendency to a cylindrical shape like the phalanges. The other 

 metacarpals bear facets on their proximal ends for articulation with each other and 

 witli the distal carpals, while their distal ends are almost flat. The phalanges are 

 dumb-bell-shaped bones with flat or gently convex ends, and they decrease in size, 

 though they do not change in shape, as the distal end of the paddle is approached. 

 In the incomplete paddle figured (Plate, fig. 4) there are thirty of those bones. 



The peine girdle (Plate, fig. 2) contains pubes, ischia, and the left ilium, the 

 other having been lost. 



The pubis may be described generally as a broad plate of bone, uniformly thin, 



