762 The American Naturalist. [September, 
cartilaginous, except a small portion at their distal ends where 
they are least developed. In the proximal row of carpals are 
two masses of rapidly forming cartilage (radiale and ulnare) 
each of which appears to have two centers of chondrification. 
The larger (the radiale, re) is almost divided into two parts; 
of these the larger and outer one is somewhat triangular in 
shape and is fitted upon the distal end of the radius, the smaller 
and inner one is nearly cireular and is contiguous to the in- 
ner margin of the distal end of the ulna. "The ulnare is com- 
posed of two oval centers, the proximal beiug about half the 
diameter of the distal one, thus giving the whole element a 
wedge-shaped appearance with its narrow end passing just 
outside the outer margin of the ulna. 
. The distal carpals are represented only by a thickening of 
tissue, or “ procartilage” of Parker, showing as yet no differen- 
tiation into separateelements. There are four radiating digits 
represented for the most part by “ procartilage,” but metacar- 
pals II' and IV are becoming cartilaginous at their proximal 
ends and metacarpal III is two-thirds cartilage. 
Stace II, (Fie. 2). 
This stage (fig. b) is but slightly more developed than the 
last. The cartilage is a little more pronounced, and digits II, 
1For the numbers to be given to the digits, see below. 
abe abe REVO ae Sea eB oh Na rer: 
