URINARY ORGANS. 



309 



p. 31 0) project ; on the summits of these the urinary tubules open 

 in varying number (between Pr and Co). The calyces are continu- 

 ous with a large cavity in the widened portion of the ureter called 

 the pelvis (Pe), and from this the ureter (Ur) passes backwards to 



Sr 

 --BF 



FIG. 242. MALE UBISOGEXITAL APPARATUS OF HEEOX (Ardea cinerea). 

 y, kidneys ; Ur, ureter,, opening into the cloaca (Cc)-at 'Sr; Ho, testis Ep epi- 

 didymis ; Vd, vas deferens, which opens at Vfr on a papilla in the cloaca 

 I , y, furrows on the ventral surface of the kidney in which veins lie embedded 

 Ao, aorta ; F, bursa Fabrieii, which opens into the cloaca at JSF 1 . 



open into the bladder on its dorsal side, sometimes nearer the apex- 

 sometimes towards the fundus. 



The urethra, arising from the bladder, is always short in the 

 female, while in the male it is drawn out into a lono- tube which 

 extends through the penis, and is lined by erectile tissue (corpus 

 spongiosum) (comp. p. 329). _ _ 



The definitive kidney (metanephros) is greatly lobulated in 



