314 The Alligator and Its Allies 



of each of these small areas. Although they show 

 no connection with the central nervous system, 

 these structures appear to be the rudiments of the 

 sympathetic nerves. 



Figure 17/ is in the region just in front of the 

 hind legs. The abdominal walls are here unfused, 

 and into the unenclosed body cavity projects the 

 intestine (i), supported by a narrow mesentery 

 and surrounded by a comparatively thick mass of 

 mesoblast. The Wolffian body and duct form a 

 mass of considerable size on each side of the 

 mesentery. The Wolffian body is cut near its 

 posterior end and consists of smaller tubules than 

 in the more anterior regions. The Wolffian ducts 

 (wd), on the other hand, are very large and are 

 much more clearly distinguishable from the Wolf- 

 fian tubules than in the preceding sections. The 

 Wolffian ridges (wr) are very marked projections 

 on the sides of the body, and in a region farther 

 caudad become especially developed as the poste- 

 rior appendages, to be described in connection with 

 the following section. Both spinal ganglia are 

 shown in this figure (sg), and in connection with 

 the left ganglion the spinal nerve {sn), extending 

 ventrally as far as the level of the Wolffian 

 duct. The sympathetic nerve rudiments do 

 not extend so far caudad as the plane of this 

 section. The dorsal end of each muscle plate 

 (mp) is seen, in this and other sections, to be 

 slightly enlarged to form a round knob; this 



