THE SPLANCHNOLOGY OF THE HEDGEHOG. 381 



rise to the middle meningeal and ophthalmic arteries. The 

 other branch passes over the cochlea, enters the skull by a 

 narrow canal near the sella turcica, and unites with the circle 

 of Willis. 



The external jugular vein is very 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 skull is carried 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 embryonic characters. 



The right lung is foiu:-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 in- 

 guinal ring, to which they are connected by a short guber- 

 naculum and cremaster. The vasa deferentia descend to the 

 base of the bladder and then enter a hollow muscular 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 tubuli, which have been found to contain sperma- 

 tozoa, and are usually regarded as vesiculse seminales. The 

 middle pair (the so-called " prostatic glands ") have a similar 

 structure 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 enclosed in wide-mouthed peritoneal sacs, 

 and a ligamentous band, the diaphragmatic ligament, extends 

 from the ovary to the posterior surface of the diaphragm. 

 The comua uteri are large and long. There are five pair of 

 teats; the anterior pair being axillary and the posterior 

 InguinaL The other three pair are equidistant, and lie along 

 the ventral surface, internal to the edge of the orbicularis panr 

 niculi. 



