512 THE AMERICAN NATURALIST. [Vor. XXXVI. 
The syndactyle hind paws have not been dissected, but a 
drawing of the palmar and dorsal surfaces is shown in Figs. 
I and 2 respectively. Walking pads and distal phalanges 
both indicate that the four digits are fused in pairs. 
I wished to determine, if possible, which toe of each fore 
paw is the extra one, and what is the nature of the evidence. 
I have been unable to learn of any account of a study on 
material precisely similar to this. The collection of facts in 
Bateson's “Materials for the Study of Variation” covers the 
ground worked over by previous authors, and this, with Poul- 
ton's papers, includes an account of all the published facts on 
the subject, as far as known to me. Previous study has been 
only on the walking pads and 
on the skeleton. Bateson 
described principally skeletal 
structures, and Poulton studied 
the walking pads. They have 
drawn their conclusions as to 
the true nature of polydactyl- 
ism from facts learned from 
these two organs only. It is, 
of course, desirable to have as 
Fio. 2. — Dorsal aspect of hind paw of abnormal complete a knowledge as pos- 
cat, showing claws fused in pairs. 
sible of the anatomy of the 
paw, as a basis for any conclusions to be drawn. I find from my 
dissections that the evidence furnished by the walking pads and 
skeletal system is borne out by the other organs mentioned. 
The general appearance of the polydactyle paw studied, apart 
from the increased number of digits, is quite different from 
that of a normal fore paw. The radial digit in the polydac- 
tyle paw extended much nearer to the end of the paw than 
the pollex normally does, the digits being more nearly of the 
same length than in the normal paw. A comparison of the 
relative positions of the ungual and middle phalanges during 
the retraction of the former will be made when we come to 
the study of the bones. 
The walking pads of the polydactyle paw (Fig. 4) differ from 
those of the normal paw (Fig. 3) in that the phalango-metacarpal 
Fu: Fic. 2. 
Fic. 1. — Palmar aspect of hind paw of abnormal 
cat, showing fused pads. 

