520 THE AMERICAN NATURALIST. 
likewise, the metacarpal of digit B is more like metacarpal A 
than the metacarpal of digit // of the normal manus is like its 
pollex. Again, the metacarpal of digit C is more like its pollex 
metacarpal A than is the metacarpal of digit ZZZ of the normal 
manus like its pollex. 
The same fact is also borne out by the comparison of the 
indices, which are mathematical expressions of the forms of the 
bones and can, therefore, be combine in the same way as 
the percentage weights. 
That the two normal radial digits have given place to three, 
each of which partakes somewhat of the nature of the others, 
is shown by a consideration of the tissue systems, and in no 
way does this explanation meet with a decided contradiction. 
The evidence of the dorsal veins is negative and not 
contradictory. 
I know of no case of polydactylism similar to the one here 
described. One which is somewhat similar is described by 
Windle (Journ. of Anat. Vol. XXVI, 1891, p. 100), who in 
conclusion says: * The musculature shows that where there is 
an additional digit on the radial side, it and the digit next to 
the index both partake of the nature of thumbs and may be 
looked — as the first and second digits of a hexadactylous 
manus.' 
In the case described in this paper, there is no reversion, 
and the anatomy of the polydactyle paw, as here worked out, 
has no bearing on either the * pre-pollex" or the “ post-mini- 
mus" theories. The abnormality seems to result purely from 
a readjustment of parts. The only definite statement which 
can be made in regard to this case is that where normally two 
digits occur, three have here appeared, and that each of these 
three partakes more of the nature of theothers than one of the 
two normal digits does of the other. 
ZOGLOGICAL LABORATORY, 
ARVARD UNIVERSITY. 

