<>0fi ANATOMY OF VERTEBRATES. 



on the concave surface of a small and simple pelvis. The ureter, 

 ib. c, c, takes the usual course to the contracted neck of the 

 bladder, ib. d : but terminates, in the male, in the urogenital canal, 

 below the vasa deferentia ; and, in the female, fig. 534, /, /, beyond 

 the uterine orifice, m, which thus intervenes between the ureter 

 and the orifice of the urinary bladder. In all respects, save the 

 place of termination of the excretory ducts and their relation to 

 the reservoir of the secretion, the urinary system of the Mono- 

 tremes adheres closely to the Mammalian type : in the Echidna 

 the mammilla slightly projects. The circumstances in which they 

 deviate from the higher Mammals approximate them to Reptiles ; 

 and it is to be observed that the deviation commences where the 

 urinary system begins to be connected with the generative organs, 

 in which the oviparous type of structure is especially manifested. 



In the Marsupialia the tubuli uriniferi terminate on a mammilla 

 which projects into the commencement of the ureter in the 

 Opossums, but does not extend beyond the pelvis of the kidney 

 in the Kangaroos. In the larger herbivorous Marsupials the 

 medullary substance forms several lateral abutments to the base 

 of the cone. In Macropus Parryi the kidneys are situated 

 six inches above the brim of the pelvis, and lie in the same 

 transverse line : they have the same relative position in other 

 Poephaga. In the Koala the right kidney is higher by its 

 whole length than the left. In Dasi/urus inacrurus and D. viver- 

 rinus the right kidney lies half an inch higher or in advance of 

 the left ; in this carnivorous genus a few branches of the renal 

 veins are distributed upon the surface of the kidney, but not 

 in the same proportion or with the beautiful arborescent dispo- 

 sition characteristic of the kidneys of the Cats, Suricates, and 

 Hyaina. In a Dcisyurus macrurus weighing three pounds eight 

 ounces, the two kidneys weighed thirteen drachms. In a P/ta- 

 lanc/ista vulpina, weighing five pounds three ounces, the two 

 kidneys weighed only ten drachms. The ureters terminate, in 

 all Marsupials, at the back of the neck of a large and pendulous 

 urinary bladder, fig. 422, /. 



In Hyrax capensis the tubuli uriniferi terminate in a promi- 

 nent and pointed mammilla; in all the large Perissodactvles, 

 e. g. Horse, Rhinoceros, Tapir, they open upon the concave sur- 

 face of the renal pelvis, and can be readily injected from the 

 ureter. Injection of the arteries of the Horse's kidney shows 

 the terminal branch, fig. 482, f\ dilating within the malpighinn 

 corpuscle, f/, and there dividing into lobes or groups of capil- 

 laries, /, i ; the returning or efferent vessel is shown at 2, e ; 

 and the continuation of the uriniferous tubule at 3, t, from the 



