304 THE ALIMENTARY TRACT, ETC. 



Just behind the root of the lung-, the peritoneum, in female speci- 

 mens,, has an opening- on each side (Ostium dbdominale tubae Fallo- 

 piae), by which the oviduct communicates with the peritoneal cavity. 



Tracing the peritoneum backwards, it passes over the ventral sur- 

 face of the kidneys so as to exclude them from the peritoneal sac : 

 in the middle line, between the kidneys, the peritoneum descends to 

 form the mesentery for the small intestine. At the inner borders 

 of the kidneys, the testes or ovaries are pushed into the abdominal 

 sac, and so possess well-marked mesenteries ; the mesovarium be- 

 comes longer towards the cloaca, but attains its greatest develop- 

 ment in the breeding season, when it is arranged in numerous folds. 

 Along the outer borders of the kidneys, in females, the peritoneum 

 again descends into the abdominal cavities to enclose the oviducts, 

 which have broad mesenteries. Towards the rectum these mesen- 

 teries are shorter and attached to either side of the bladder by a 

 well-marked free border : as the middle line of the bladder is 

 attached by the peritoneum to the rectum, two distinct pouches 

 (Cava recio-vesicalia) are formed, which descend deeply into the 

 pelvic cavity. The upper walls of these pouches are pushed in be- 

 tween the urostyle and the rectum, and together form a strong 

 meso-rectum, which is. longer near the I alvnla BauJiinii and con- 

 tinuous with the mesentery of the small intestine. The hinder 

 portion of this mesentery is very short, and only covers the lateral 

 walls of the rectum. 



With the exception of a small portion of its dorsal surface, which 

 is attached to the rectum, the whole surface of the bladder is covered 

 with peritoneum. 



The mesentery of the alimentary canal commences in connection 

 with the oesophagus between the roots of the lungs ; it is attached 

 to the dorsal surface of the liver, covering- the posterior caval vein, 

 and is attached to the gall-bladder. From this point it extends, as 

 a free, arched fold, to the concave right border of the stomach, 

 which is completely surrounded by peritoneum. 



The gastro-duodenal fold (Li (/amentum gastro-duodenale) extends 

 from the stomach to the pylorus and includes the pancreas. The 

 hepato-duodenal fold (L'uj. Jiepato-duodenale) extends from the portal 

 fissure of the liver to the duodenum. 



The mesentery of the small intestine is broad and arranged in 

 folds, which follow the curves of the intestine; and is attached in 

 the middle line, immediately beneath the vertebrae, where it encloses 

 the aorta. 



