XUI 



PHYLUM OHORDATA 



473 



The special features of the middle ear with its auditory ossicles, 

 and of the external ear, have been already referred to. 



Urinogenital Organs. — The kidneys are of somewhat com- 

 pressed oval shape, with a notch or hilus on the inner side. They 

 are in close contact with the dorsal wall of the abdominal cavity, 

 the right being somewhat in advance of the left. Towards the 

 hUus the tubules of the kidney converge to open into a wide 

 chamber — the pelvis — which forms the dilated commencement of 

 the ureter. When the kidney is cut across, its substance is seen to 



Fig. 1097.— tepus cuniculus. The urinogenital organs ; A, of male ; B, of female ; from the 

 left side (half nat. size). The kidneys and proximal ends of the ureters, in A tlie testes, and 

 in 5 the ovaries, Fallopian tubes and uteri are not shown, an. anus; hi. urinary bladder ; 

 c. c. corpus cavemosum ; c. s. corpus spongiosum ; c. gt. Cowper's gland ; g. cl. apex of clitoris ; 

 jf-i). apex of penis ; p. gl. perineal gland ; p. gV. aperture of its duct on the perineal space ; jir. 

 anterior, jyr'. posterior, and pr". lateral lobes of prostate ; ret. rectum ; r. gl. rectal gland ; 

 w. g. a. urinogenital aperture ; w. w. uterus masculinus ; ur. ureter ; va. vagina ; ij^. vesti- 

 bule ; V. d. vas deferens. (From Parker's Zoo^om?/.) 



be divided into a central mass or medulla and a peripheral portion 

 or cortex. An adrenal (sii/prarenal) tody lies in contact with the 

 anterior end of each kidney. The ureter (Fig. 1097, iir.) runs 

 backwards to open not into a cloaca, but directly into the urinary 

 bladder (hi.). The latter is a pyriform sac with elastic walls which 

 vary in thickness according as the organ is dilated or contracted. 

 In the male the openings of the ureters are situated nearer the 

 posterior, narrower end or neck than in the female. 



In the male Rabbit the testes are oval bodies, which, though in 

 the young animal they occupy a similar position to that which 



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