5 18 THE AMERICAN NATURALIST. [VoL. XXXVI, 
Broop VESSELS. 
The arrangement of the veins on the dorsal surface of the 
normal and the polydactyle fore paw is shown in Figs. 11 and 12. 
The only points that can be taken as homologous for deter- 
mining the corresponding veins in the normal and polydactyle 
paw are the most distal point of the loop formed by the anas- 
tomosis of the ulnar (v.7/7.) with the radial (v.7.) vein. This 
point in both normal and polydactyle paws seems to be between 
digits marked /// and 
IF. Starting from this 

are three branches, and 
in the polydactyle paw 
four branches, which 
contribute to the radial 
vein. These facts 
suggest the conclusion 
that the extra digit of 
the polydactyle paw is 
on the radial side; but 
owing to the uncer- 

Fic. rr. 
Fic. 11. 1 aspect of lef t howing tainty of the exact 

Ss 
shea veins. v.udn., ulnar vein; v.r., radial vein. position of this point 
ie Wem S src Pelion left manus of polydactyle cat, of reference, the evi 
dence from the veins 
is of less value than that from some of the other organs. 
In studying the arteries the only fact which throws any light 
on the problem is the relative size of the digital branches from 
the palmar arch (Figs. 13, 14). The branch which supplies 
the radial digit is small in both the normal and the polydactyle 
paw. In the normal paw the branch to the index is as large as 
the branches to each of the other three digits; but in the poly- 
dactyle paw the branches to digits 4 + B and B + C (Fig. 14), 
while about equal to each other in size, are much smaller than 
those to the external digits. 

