The Development of the Alligator 307 



irregular; except at the extreme anterior end and 

 at one or two other places, it lies in close contact 

 with the floor of the neural tube. Directly under 

 the notochord lies, in the posterior half of the figure, 

 the large dorsal aorta (ao). The pharynx (pJi), 

 opening between the end of the forebrain and the 

 thick mandibular fold (across which opening the 

 amnion, a, of course extends), is a funnel-shaped 

 space which passes out of the plane of the section 

 toward the posterior end of the figure. Its thick 

 endodermal lining extends to the mandibular fold 

 on the ventral side, while on the dorsal side it 

 gradually thins out and becomes continuous with 

 the thin ectoderm that extends over the forebrain. 

 Just back of the mandibular fold is the bulbus {b) , 

 and back of that is the edge of the ventricle (vii). 

 Posterior and dorsal to the ventricle the liver (li) 

 is seen as an irregular mass of cells, and dorsal to 

 the liver one of the Wolffian bodies (wt) is cut 

 through its extreme edge. 



STAGE XIV 



Figures 17-17^ (Plates XXIIL, XXIV.) 



Body flexure has increased until now the fore- 

 brain and tail are almost in contact (Fig. 17). 

 The eye has developed somewhat; the ear vesicle, 

 which is not shown in the figure, is small and seems 

 to lie nearer the ventral side ; the nasal pit is much 

 larger and is crescentic in shape. The hyomandib- 



