THE URINARY AND GENERATIVE SYSTEMS. 209 
pair of ceca there may be a single cecum or there may be 
nothing of the kind whatever. 
The rectum opens posteriorly into the terminal chamber of 
the alimentary canal, which is called the cloaca. The latter is 
a capacious rounded space, into which the urinary and generative 
ducts also open, the whole communicating with the exterior by 
a single aperture, the vent. 
A glandular structure, called the bursa Fabricii, also opens 
upon the wall of the cloaca into its cavity. 
A gland, called the pancreas, which supplements by its secre- 
tion the action of the saliva, lies embraced by the duodenal 
fold of the intestine. Two or three ducts from it enter the 
intestine near its commencement. A little further down, the 
ducts of the liver convey its secretion, the bile, into the intes- 
tine. It is divided into two main lobes, and may or may not 
be provided with a gall-bladder. 
A small round or oval body, called the spleen, lies not far 
from the stomach, 
Tur URINARY AND GENERATIVE SYSTEMS. 
The urinary system consists of two kidneys, the ducts of 
which—the wreters—pass backwards and open into the cloaca, 
behind where the alimentary canal opens into it. The kidneys 
are soft in texture, and sometimes—as in the Grebe and Coot— 
are more or less blended together at their hinder ends. They 
are dark-coloured and firmly fixed upon the ventral sur- 
face of the dorsum of the trunk, especially within those 
cavities of the sacrum before described *. At the anterior end 
of either kidney is a small yellowish body named the supra- 
renal capsule. 
The testes, or essential male organs, are a pair of oblong or 
more elongated bodies placed on the ventral side of the ante- 
rior part of the kidneys. Each consists of a mass of most 
minute and highly convoluted tubes. The testes: vary much 
in size according to the season of the year, enlarging greatly 
at the breeding-season. ‘Their secretion is conveyed outwards 
by two long, more or less convoluted tubes—the vasa deferentia 
—which pass back beside the ureters and open, each on a 
papilla, in the cloaca, one on each side of the openings of 

* See ante, p. 174. 
