516 THE AMERICAN NATURALIST. [Vor. XXXVI 
four external digits of the polydactyle paw correspond to 
the external four in the normal cat, and that the extra digit 
occurs on the radial side of the four external digits, an infer- 
ence which, with some modifications, seems to be confirmed 
by other facts. 
Muscle extensor carpi ulnaris (Figs. 5, 6, ext.carp.uln.) in 
both normal and polydactyle paw is inserted on the ulnar 
metacarpal. 
^. The indicator (Fig. 7, ext.2x.) is somewhat variable in respect 
to its insertion, even in normal specimens, sometimes supplying 
the pollex, index, and medius, sometimes only the pollex and 
index. In the polydactyle paw a peculiar arrangement exists, 
in that there are two muscles in place of one. That which, 
from relative position and insertion, seems to correspond to 
the normal one (Fig. 8, exzzx.7) is distributed to the second 
(5) and third (C) digits. 
In addition to this muscle there is under it, and distinct 
from it, another muscle (ext.2x.2), which passes in the same 
general direction to the two internal digits (A and B, Fig. 8). 
This muscle has a more distal origin than does the one sup- 
plying digits B and C; it originates from the dorsal border 
of the ulna and passes directly over the muscle extensor meta- 
carpi pollicis (ext.mt' carp poll). Comparisons of the two indi- 
cators with each other and with the normal muscle seem to 
point to a readjustment to meet a new condition of the manus. 
In both the normal and the polydactyle manus the radial 
metacarpal furnishes insertion for the extensor metacarpi polli- 
cts (Figs. 7, 8, ext.mt carp poll). 
Muscle flexor carpi radialis in both the normal and the poly- 
dactyle paw has its tendons inserted on the proximal ends of 
the palmar surface of the second (counting from the radial 
side) metacarpal. 
he ulnar part of the flexor sublimis digitorum in both 
normal and polydactyle paws has tendons extending to the 
first and second digits, counting from the z/zar side (Figs. 
3, 4, Jix.sb Ldg., while the tendons from the radial part of 
the muscle extend in the normal paw to the four, and in the 
polydactyle paw to the five, digits nearest to the radial side. 

