DR. A. GUNTHER’S DESCRIPTION OF CERATODUS. 
545 
I have to add a few words on the termination of the intestinal tract, and on the open- 
ings of the neighbouring excretory organs (Plate XL. figs. 1 & 2). The vent ( v ) lies in 
the median line of the abdomen, and leads into a very short and rather narrow cloaca, 
which is subdivided into two by a projecting fold of the dorsal wall of the rectum (r). 
This fold answers also the purposes of a valve, preventing the contents of either of the 
cloacal divisions from entering into the other. The abdominal portion of the cloaca 
passes uninterruptedly into the cavity of the rectum, the dorsal portion (u) being a small 
receptacle for the urine and generative products. 
Immediately behind the vent are the two peritoneal openings (w), leading directly into 
the peritoneal cavity. 
Liver (Plate XXXIX.). 
A general description of the liver and its situation in the abdominal cavity has been 
given above. Its texture is spongious, not dense, in consequence of the great width of all 
the venous and biliferous cavities and ducts in its interior ; certain portions may be inflated 
like the lung of a mammal. The gall-bladder (e) is very large, pear-shaped, and con- 
tinued into the ductus choledochus, which is rather wide in its commencement, and 
enters by a small opening (e') below the pyloric valve on the right side of the ventral 
wall of the abdomen. In order to reach this spot, the ductus choledochus has to traverse 
a rather long course below the mucous membrane of the stomach. Of the ductus hepa- 
tici, one, coming from the lateral lobe of the liver, and running nearly along the entire 
length near to the inner surface of the lobe, is particularly conspicuous. These ducts 
are collected into one trunk, which enters the ductus choledochus in the upper half of 
its course, before it has reached the wall of the stomach. The common opening of the 
hepatic ducts is much wider than that of the ductus choledochus. 
The vena cava , which ascends along the line of attachment of the peritoneum to the 
right testicle (Plate XL. w), enters the hindmost extremity of the lateral lobe of the 
liver ; it becomes much wider within this lobe, and penetrates through its substance, 
through the bridge connecting the two lobes, and through the upper lobe, where it re- 
appears to enter the sinus venosus communis. Its inner walls are perforated by the 
openings of numerous small branches ; and the venous system of the liver can be filled 
with matter of injection from either end of the vena cava. 
The arteria coeliaca, which takes its origin on the right side of the aorta, runs round 
the bridge, connecting the lateral lobe of the liver with the upper one, and divides into 
several branches on entering the intestinal canal at the end of the axis of the spire. 
One of its branches is destined for the liver itself, another for the dorsal portion of the 
lung. At the same spot several venous trunks leave the intestine, and, entering the liver, 
where they branch off into smaller stems, represent the portal system. 
Urojooetic Organs (Plate XLI.). 
The kidneys (c, c ') lie in the posterior part of the abdominal cavity, being only about 
3 inches long. They are paired, each being firmly attached to the testicle (b, V) 
4 f 2 
