472 ZOOLOGY. 
1st, the sinws venosus ; 2d, both auricles; 3d, the ventricle ; 
4th, the truncus. 
In front of and below the heart may be seen the trachea, 
easily recognized by the hard rings of cartilage, and having 
the larynx just in front of the aortic arches and giving off 
two branches posteriorly, the bronchi, which run directly to 
the lungs. The trachea overlies the wsophagus, which ter- 
minates in the stomach (S#). On either side of the trachea 
lies a thyroid gland (th). 
The liver (Zi) is a large brown mass, composed of two 
lobes, of which the left is the larger, and subdivided into 
two. Between the two lobes lies a small greenish sac, the 
gall-bladder (4). The liver receives a large vein (pv) from 
the kidneys ; this is the portal vein, which distributes to the 
liver the blood which has already once passed through the 
capillaries of the other abdominal viscera. The hepatic vein 
takes the blood from the liver directly to the heart. 
The stomach (S¢), when in sitw, lies on the left side of the 
abdominal cavity, its esophageal end being the largest ; it 
leads directly into the intestine, which is of uniform width 
throughout, but terminates in the dilated rectum (A), which 
in its turn opens into the cloaca. To the ventral surface of 
the cloaca is appended the bladder (82). Imbedded in the 
mesentery near the commencement of the intestine is a pale 
compact mass, the pancreas, not represented in the figure, 
and a little farther from the stomach a small round dark 
body, the spleen (Sp). 
The kidneys (7) are two elongated deep red bodies, upon. 
which lie a number of yellow spots, the adrenal glands. 
The renal ducts arise from the outer and anterior portion of 
the kidneys and then run backwards as two white convoluted 
canals (vd), at first very narrow, then widening, and end- 
ing with a dilatation immediately before they open into the 
cloaca. These ducts serve at once as wreters and vasa defer- 
entia. In front of the kidneys lie a pair of oval yellow 
bodies, the testes (Ze). The female has both ureter and 
oviduct. The ovary varies greatly in size and appearance. 
according to its condition. The oviduct is a very long con- 
voluted tube running from the a backwards to 
