272 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
mal, and its proximal end is relatively large. In digit ur the radial 
process of the metacarpal bone, a special character of the manus in recent 
swine, is greatly reduced, and as a result scarcely touches the trapezoid, 
while metacarpal 11 comes in contact posteriorly with the os magnum. 
The trochlear ridges of the metacarpals are retained, and the phalanges 
show no modifications in form. 
IV. III. 
Fic. L. — Posterior view of left polydactyle manus of the pig, showing innervation. 
nm. m., median nerve; 1, branch of median nerve supplying the supernumerary digit (1). 
3 natural size. 
The muscles are not much modified, for the extra digit is small and 
functionless. In two instances, however, the tendon of the extensor 
metacarpi obliquus muscle is inserted into the proximal end of digit 1. 
This is an interesting condition, as in normal five-toed animals this 
muscle is likewise always inserted into the metacarpal of the pollex. 
