496 



THE URINARY APPARATUS. 



applied, and on which they are moulded. In many birds, nevertheless, three portions, 

 more or less separated by fissures, may be recognised. The ileo-lumbar portion (so named 

 because of its constant position in this region) is the most advanced ; it is often the 

 largest. The middle is the narrowest ; it is turned towards the ileo-sacral region, to enter 

 the pelvis. The posterior is contained in that cavity, and is again larger. These two 

 latter portions are designated as the anterior or superior pelvic, and the inferior or deep 

 pelvic portions. Their internal and superior border is often notched by a series of trans- 



Fig. 254. 



Fig. 255. 



Fig. 256. 



KIDNEYS OF THE OX. 



Fig. 254. Right kidney, viewed on its upper and external face. Fig. 255. Left 

 kidney, from its internal and inferior face ; a, Pelvis ; 6, 6, 6, Branches of the 

 pelvis terminating in calices ; c, Ureter ; d, Renal artery. Fig. 256. The calices 

 in the left kidney. The contents of the hilus, including the branches of the 

 pelvis, have been removed to show the tubercles at the bottom of these calices. 

 Only seven are visible, the others being beneath the borders of the renal fissure. 



verse fissures produced by the protrusion of the transverse processes of the sacral verte- 

 brae, as the lungs are furrowed by the projection of the ribs." 1 



The excretory apparatus is incomplete, and is only formed by the ureters, which open 

 into the cloaca, where the urine is mixed with the faeces. Only one bird, the Ostrich, 

 possesses a bladder, which is disposed in a particular manner. 



COMPARISON OP THE URINARY APPARATUS OF MAN WITH THAT OP ANIMALS. 



1. Kidneys. The two kidneys of Man have, like those of the smaller domesticated 

 animals, the same shape that of a haricot bean. The average weight is about from three 

 to five ounces. Contrary to what is observed in the Horse, the left kidney is more 

 voluminous than the right, and is higher. 



The kidneys are simple externally, though their tissue is disposed in distinct lobes, 

 which number from eight to fifteen., and are composed of a Malpighian pyramid and a 



1 Cuvier, 'Anatomic Comparfe,' 2nd edition. Paris, 1836-46. 



