312 The Alligator and Its Allies 



Figure 17 d is in the region of the posterior end 

 of the heart (Jit), which is cut through the tip of 

 the ventricle, and the anterior end of the liver 

 (li), which has the appearance of a mass of darkly 

 stained cords or strands of cells surrounding a 

 large blood-vessel (mv). This blood-vessel may 

 be called the meatus venosus, though it is not sepa- 

 rated by any line of demarcation from the auricle. 

 A few sections anterior to this region the meatus 

 venosus opens dorsally into a large vessel on each 

 side (dc) , which at first glance seems a part of the 

 body cavity, but which is in reality the ditctus 

 Cuvieri, formed by the union of the anterior and 

 posterior cardinal veins. An irregular, crescentic 

 cleft (be), lying medial and parallel to each of the 

 Cuvierian vessels, is the body cavity. In the upper 

 angle of this cavity is a granular mass, the glcmeru- 

 lus, that of the left side being accompanied by 

 the extreme anterior end of the Wolffian duct. In 

 the rounded mass of mesoblast, between the cleft- 

 like regions of the body cavity, the lung rudiments 

 (In), and the oesophagus (oe) are seen as three 

 small, circular openings; that of the oesophagus is 

 somewhat smaller than the other two. The noto- 

 chord (///), spinal cord (sc), and muscle plates (mj>) 

 have almost the same appearance as in the preced- 

 ing section. A spinal ganglion (sg) is seen on 

 each side of the spinal cord; the one on the left 

 shows a well-defined spinal nerve (5/7), which may 

 be traced ventrally as far as the end of the muscle 



