608 



ANATOMY OF VERTEBRATES. 



Section of part of Human kidney : nat. 



lobulated. In the human kidney the tubuli are grouped into 

 from twelve to fifteen conical bundles, the apices of which project 



into a common pelvis ; but 

 occasionally two cones 

 combine to terminate by a 

 common mammilla : in fig. 

 483 are shown three cones, 

 in section, with the rela- 

 tive position thereto of the 

 arteries, «, and the veins, 

 b. In the foetus the cor- 

 tical part is subdivided 

 like the medullary, but the 

 clefts become obliterated in 

 the growth of the kidney. 



Quadrmnana have a sin- 

 gle mammilla ; but in the 

 larger kinds it is extended, 

 and the tubuli are partially 

 grouped into bundles near the cortical substance. The kidney in 

 48 the Suricate, Viverri- 



das, Hyamas, and Fe- 

 lines is chiefly remark- 

 able for the arborescent 

 disposition of the veins 

 on or near the surface ; 

 the mammilla is single, 

 as it is, also, in the 

 Mustelidce, Canidce, and 

 Subursidce. In Beais, 

 Seals, and Whales, the 

 kidney is divided into 

 numerous lobes or re- 

 nnles, in the Walrus 

 amounting to three or 

 four hundred, and in the 

 Porpoise, fig. 427, E, to 

 even a greater num- 

 ber. Each renule lias 

 its own capsule, which 

 is removed at a, a, 

 fig. 484 ; a section of 

 the renule shows it to be composed of a cortical and medullary 



Portion of the kidney of a Pornoise. cclxxxvi. 



