The Development of the Alligator 329 
paddle-shaped manus and pes the digits may be 
faintly seen. The tail is very long and is spirally 
coiled, the outer spiral being in contact with the 
frontal region of the head. The jaws are com- 
pletely formed, the upper projecting far beyond 
the lower. The elliptical outline of the eyes is 
noticeable, but the lids are still too little devel- 
oped to be seen in this figure. The surface of the 
embryo is still smooth and white. 
STAGE XX 
FIGURES 23-230 (PLATE XXVII.) 
In this surface view (Fig. 23) several changes are 
seen, though no very great advance in develop- 
ment has taken place. The outlines of the digits 
(five in the manus and four in the pes) are now 
well defined; they even project slightly beyond 
the general outline of the paddle-shaped part. 
The tail has begun to straighten out, and it now 
extends across the front of the face. The lower 
jaw has increased in length, but is still shorter 
than the upper. The eyelids, especially the upper, 
are beginning to be discernible in surface view. 
Though still without pigment, the surface of the 
body is beginning to show by faint transverse 
lines the development of scales; these lines are most 
evident in this figure in themiddle region of the tail, 
just before it crosses the nose. 
A sagittal section of the entire embryo (except 
