278 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 
the trapezoid, on the contrary, is small and laterally compressed, as is 
also the proximal end of metacarpal u. 
The tendons of the muscles and the nerve of digit 1 bifurcate (Fig. Q, 1). 
This intermediate stage leads up to conditions in which there are two 
complete and entirely distinct digits. The duplication may extend even 
nN. Me 
IV. III. 
Fie. Q.— Posterior view of left polydactyle manus, showing innervation. 1%, 1°, 
supernumerary digits; 1, first branch of median nerve, which bifurcates twice, the branches 
from the second bifurcation going to digits 1¢ and 1%. 4% natural size. 
to the carpus, and the two digits thus formed may be nearly as large as 
the functional digits (11 and Iv) of the manus. Six such cases were 
examined. In the typical condition (Plate 13, Fig. 21) the supernu- 
merary digits (1%, 1’) are somewhat smaller than mi and iv. Each 
