280 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
(ext. mt’carp. ob.) is large, and its tendon, instead of being inserted as 
normally into the proximal end of metacarpal 11, continues down to the 
distal phalanges of the supernumerary digits, into which it is inserted by 
three slips. In two cases this muscle was strengthened by a strong slip 
from the great extensor of the metacarpus. This is an interesting case 
IV. iii. : 
Fic. S.—Posterior view of left polydactyle manus of the pig, showing flexor 
muscles. flz. perf., flexor perforatus tendons; flx. perf’., flexor perforans; 1%, 1°, super- 
numerary digits. % natural size. 
of adaptation, and shows what a strong influence the functional capacity 
of the digits has on the development and structure of their muscles. 
Of the flexor muscles, the perforans (Fig. S, flz. perf.) gives off a 
large tendon to the extra digits; this divides, and a branch is inserted 
into each ungual phalanx. The flexor perforatus (fl. perf.) also sends 
a large tendon to the extra digits, which bifureates in the region of the 
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