URINARY ORGANS. 121 



URINARY ORGANS. 



THE Kidneys in the Bird are very large and impacted within deep 

 depressions in the pelvis, which they completely fill up ; they com- 

 mence immediately beneath the lungs, and like those organs, they 

 retain the impressions of- the lowermost ribs, but particularly of the 

 transverse processes of the sacral bone. They almost invariably 

 consist of three principal lobes, of which the middle one is generally 

 the smallest, the anterior frequently the largest, as in the Rapaces, 

 but in other cases, as the Pelican, the posterior lobe. In the Ra- 

 paces, Gallinae, and Columbidae, they are separated from each other 

 by a wide interval, in which the aorta passes, and do not occupy 

 the whole extent of the cavity of the sacrum, part of it being 

 occupied by air-cells. In other Birds, as the Passeres, they 

 come in contact in the median line, and even coalesce in several 

 species, e. g. Lanius Excubitor, and more rarely in Ardea cinerea. 

 The kidneys form, however, as a rule one blended mass in the Loons 

 (Colymbus s. Podiceps). In the Coot (Fulica atra) the kidneys 

 are divided on their postero-superior surface into a great number 

 (about 60) small lobules, which are only loosely connected together 

 by cellular tissue. The kidneys are of a brown color, and friable 

 texture ; the delicate urinary canals give off short lateral branches, 

 presenting thus a pinnatifid appearance, and do not terminate upon 

 conical papillae. The urine of Birds is very rich in earthy constit- 

 uents, and contains but little water, so that the kidneys frequently 

 appear, after death, as if injected from a deposite of urate of 

 ammonia having taken place and filled their tubes. In the Strti- 

 thious birds papillae and calyces are met with in the kidneys, and 

 in the Ostrich a true renal pelvis. Several excretory ducts gener- 

 ally proceed from the kidneys to form the ureters, which descend 

 along the anterior surface of the kidneys, and terminate by perfora- 

 ting the cloaca posteriorly and superiorly. A proper urinary bladder 

 is absent, though the ureters in many Birds open into a distinct pouch- 

 shaped dilatation of the. cloaca, bounded above and below by a valvu- 

 lar fold, separating it on the one hand from the urethro-sexual cavity, 

 on the other from the orifice of the rectum, and which is by many 

 writers viewed as a rudimentary urinary bladder ; this structure is 

 most strongly developed in the Ostrich. 



A pair of yellow or orange colored Suprarenal Capsules, of the 

 shape of millet-seeds, flat and usually of small size, are constantly 



