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) . In the 

 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 {tn). 

 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. 



