448 THE ANATOMY OF VEETEBEATED ANIMALS. 



thick, while the fornix is comparatively thin and slender. 

 The anterior commissure is very stout. In this circum- 

 stance, as in the small corpus callosum, the brain of the 

 Hedgehog closely approaches that of the DideJpliia and 

 Omithodelphia. There is no trace of a posterior cornu, or 

 calcarine fissure, and the lateral ventricle extends forwards 

 into the olfactory lobe. The optic nei-ves are very slender ; 

 the corpora genicidaia externa are large and prominent ; the 

 nates are smaller than the testes, and transversely elongated. 

 The cerebellum has a large vermis and small lateral lobes ; 

 the floccidi are prominent and are lodged in fossae of the 

 periotic bones. The pons Varolii is very small ; the corpora 

 trapezoidea proportionally large. 



The spinal cord is remarkable for its thickness, and, at 

 the same time, for its brevity, as it ends in the middle of 

 the dorsal region. As a consequence of this an-angement 

 the Cauda equina is particularly large and long. 



The stomach is simple, but the miicous membrane of the 

 considerable cardiac dilatation is thrown into numerous, 

 and very strong, longitudinal rugse. The intestine is about 

 six times as long as the body, and presents no distinction 

 into small and large ; nor is there any coecum. The liver 

 is divided by deep fissui-es into six lobes; a central one which 

 bears the gall-bladder, a bifid spigelian lobe, and, on each 

 side of these, two other lobes. The pancreas is a large and 

 in-egvdarly ramified gland ; and the spleen is elongated and 

 trihedral. 



The pericardium is extremely thin. The arteries arise 

 from the arch of the aorta, as in Man, by an anonyma, a 

 left carotid and left subclavian. The course of the internal 

 carotid is remarkable. When it reaches the base of the 

 skull it enters the tympanum and there divides into two 

 branches, of which one traverses the stapes, and passing 

 forwards in a groove of the roof of the tympanum, enters 

 the skull and gives 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. 



