THE SPLANCHNOLOGY OF THE HEDGEHOG. 449 



The external jugular vein is veiy much more capacious 

 than the internal, the latter being very small and hardly 

 traceable to the internal jugular foramen. It is by the 

 external jugular vein, in fact, that the great mass of the 

 blood within the skuU is eari'ied away, a foramen in the 

 squamosal bone allowing of a free communication between 

 the external jugular vein and the lateral sinus. There is a 

 left superior vena cava, which winds round the base of the 

 left auricle, receives the coronary vein, and opens into the 

 right auricle. The vascular system thus retains many 

 emliryonic characters. 



The right lung is four lobed ; the left may possess from 

 one to three lobes. 



Two ossifications, one on each side of the opening for the 

 aorta, occur in the diaphragm. 



The testes of the male do not leave the cavity of the 

 abdomen, but they descend as far as the inner side of the 

 inguinal ring, to which they are connected by a short 

 gubernaculum and cremaster. The vasa deferentia de- 

 scend to the base of the bladder and then enter a hollow 

 miiscular sheath on their way to a " chamber," which is 

 lodged in the distal end of that sheath. This " chamber" 

 passes into the penial urethra; the cystic urethra opens 

 into it by a narrow slit in its front wall; and it receives the 

 ducts of three pair of appendages. The proximal pair 

 consist of a multitude of ramified tiibuli, which have been 

 found to contain spermatozoa, and are usually regarded as 

 vesicula3 seminales. The middle pair (the so-called " pro- 

 static glands ") have a similar stracture and have also been 

 observed to contain spermatozoa. The lowermost pair are 

 Cowper's glands. The " chamber " appears to represent the 

 urogenital sinus of the embryo, which has not become 

 differentiated into prostatic and bulbous urethra. 



The ovaries are inclosed in wide-mouthed peritoneal sacs, 

 and a ligamentoiis band, the diaphragmatic ligament, ex- 

 tends from the ovary to the posterior surface of the dia- 

 phragm. The cornua uteri are large and long. There 

 are five pair of teats ; the anterior pair being axillary and 



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