* 312 The Alligator and Its Allies 
Figure 17d is in the region of the posterior end 
of the heart (ht), 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 ductus 
Cuviert, formed by the union of the anterior and 
posterior cardinal veins. An irregular, crescentic 
cleft (bc), 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 
(lu), and the cesophagus (oe) are seen as three 
small, circular openings; that of the cesophagus is 
somewhat smaller than the other two. The noto- 
chord (nt), spinal cord (sc), and muscle plates (mp) 
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 (s7), which may 
be traced ventrally as far as the end of the muscle 
