PRENTISS : POLYDACTYLISM IN MAN AND DOMESTIC ANIMALS. 265 
wedge-shaped and divided into two facets of nearly equal size, the radial 
for articulation with metacarpal 11, the ulnar for the large process of 
metacarpal ut. The os magnum articulates distally with the third meta- 
carpal only; the unciform has distally a small facet for the ulnar pro- 
cess of metacarpal 111, a large one for metacarpal Iv, and a small facet 
laterally placed for metacarpal v. 
Fic. G. — Left manus of Ancodus brachyrhynchus, showing carpals and metacarpals. 
I-V, first to fifth metacarpals; lun., lunar; 0s mag., os magnum; scph., scaphoid; trz., 
trapezium ; trzd., trapezoid; un., unciform. 3 natural size. (After Scott.) 
If we compare the carpus and metacarpus of the pig with those of 
fossil swine (Palaeochoerus and Hyopotamus or Ancodus) figured by 
Kowalevsky (’73) and Scott (95), we find some remarkable differences. 
In Hyopotamus (Ancodus of Kowalevsky) the trapezium (Fig G.) is 
nearly as large as the trapezoid, and articulates superiorly with the 
scaphoid, inferiorly with the metacarpal of digit 1. The trapezoid has 
