730 
bad preservation. 
individual variation. 
THE AMERICAN NATURALIST. 
[VoL. XXXIII. 
It is believed by the author that the varia- 
tion shown is the result of the preservation and not a real 
This cannot be definitely stated however. 
o. (LENGTH 
CoLLEC-| COLLECTION. IN Cora or PAnR | CONDITION OF Paps on HANDS. 
TION IM. ee: | 
67 H.M.C 31 (Slightly developed. 
58 P&S, 36 “ Slightly developed. 
2 P.&S 42 | Well developed. Well developed. 
32 “ 44 “ “ 
21 = 55 . Fairly developed. 
249 H. M.C 57 “ Mounts ” barely shown. 
N.Y, LLE 65 p 
183 H.M.C Fairly developed Fairly developed on one hand. 
6 P&S 70 Slightly developed. |Not present as pads. 
IIo H. M.C 76 - 
20 P.&S. 80 | Well developed. Fairly developed. 
149 H.M.C 85 Fairly developed. (Not present as pads. 
30 P.&S. 97 |Not present. " 
8 1 100 Poorly developed. /Faintly developed. 
3 H.M.C 103 |Not proest, Not present as pads. 
216 ” 104 + 
5I P. & S. 105 |Scarcely discernible. + 
10 ig 115 |Not — ed 
12 fy 120 se 
68 H.M.C. 120 |Scarcely discernible. “ 
239 “ I 5° “ “oe 
H. ard Medical School Collection. 
P. & S. = Collection ne peo of Physicians and Surgeons, Columbia Univ. 
N.Y. L. I. H.= w York Lying-in Hospital. 
Sections (Figs. 2 and 3) show the pad to be the result of the 
growth of the mesodermic tissue beneath, rather than an epi- 
dermic thickening. A cross-section (Fig. 4) of the right hind 
foot of a cat embryo in the region of the Anlagen of the walk- 
ing pads shows an essential similarity in their form, position, 
and structure with the mounds on the human feetal foot (Fig. 2). 
Since the interdigital position precludes the possibility of 
the mounds being merely contour lines resulting from the influ- 
ence of the joints or digits, we may infer from the fact that the 
position is characteristic of walking pads that we have here 
structures of this kind. Further evidence lies in the fact that 
” 
