390 CHORD ATA. 



inguinal canals. Through each of these canals there passes 

 a sper7natic cord with genital artery and vein to the testis from 

 the lumbar region.. The testis is partially surrounded by 

 an epididymis consisting of coiled tubes, the vasa efferentia, 

 which unite to form the vas deferens. This duct leaves the 

 scrotal sac by the inguinal canal and passes up round the 

 ureter of the same side, then backwards to open into the 

 urethra. The testes in the young rabbit occupy the normal 

 position in the neighbourhood of the kidneys, but by a 

 process called the descensus testiculorum they pass down- 

 wards and into the scrotal sacs. 



The swollen base of the two vasa deferentia, as they 

 enter the urethra, is often termed the uterus masculinus. In 

 the same position are the prostate glands opening into the 

 urethra, and posterior to them are a pair of Cowper's glajids. 

 The urethra passes along the posterior surface of the penis^ 

 which is formed of vascular erectile tissue. 



In the female the ovaries are small oval bodies attached 

 by mesentery to the dorsal abdominal wall. The oviducts 

 are paired tubes of the same size. Each has three parts, 

 viz.: — the anterior portion or Fallopian tube, of small calibre, 

 and opening into the abdominal cavity by a large funnel ; 

 the middle portion or uterus, which has thick muscular 

 walls and is used for the retention of the young during 

 gestation ; the third portion or vagina, which in the rabbit 

 is fused with its fellow, resulting in a single wide vagina, at 

 the anterior end of which opens the os of each uterus, and 

 posteriorly it leads into the urethra which is, in the female, 

 known as the vestibule. There are Co7Vper's glands, as in 

 the male, and a vestigial penis called the clitoris. The 

 opening to the exterior is called the vulva. 



The brain may be isolated by careful removal of the roof 

 of the skull. It is chiefly remarkable for very large cerebral 

 Nervo hemispheres which are connected across by a 



large band called the corpus callosum, for the 

 lateral expansion and coiling of the cerebellum, for the 

 division of the optic lobes into four, called the corpora 

 quadrigemina, and for the presence of twelve cranial nerves, 

 the spinal accessory and hypoglossal being added to the ten 

 of the skate. 



