The Development of the Alligator 333 
with each other and open almost immediately into 
the pharynx. The rather complicated structures of 
the nasal passages of the alligator have been de- 
scribed by the writer in another paper (57). Inthe 
lower jaw the cartilage (mk) is seen on either 
side and several bands of muscle are developing in 
the mesoblast. Two deep grooves give form to 
what may be called the rudimentary tongue (é). 
In both jaws one or two tooth rudiments (to) may 
be distinguished as small invaginations of ectoderm. 
STAGE XXI 
FIGURE 24 (PLATE XXVII.) 
In this stage the curvature of the body and tail is 
less marked than was seen in the last surface view. 
The body has increased greatly in size, so that the 
size of the head is relatively not so great. The 
size of the eye in relation to that of the head is 
much diminished also. The five anterior and four 
posterior digits are well formed, and their claws 
are of considerable size, though of course not 
present on all the digits. The outlines of scales 
may be traced from the tip of the tail to the skull; 
they are especially prominent along the dorsal 
profile. The skin is just beginning to show traces 
of pigment, which is, however, not shown in the 
photograph. The umbilical stalk is seen project- 
ing with a loop of the intestine from the abdominal 
wall; this is shown more clearly in the next stage. 
