1904.] 



OP THE BRAINS OF MAMMALS. 



■187 



is possibly the equivalent of the anterior choroid artery of Man. 

 I did not find it in the other rodents. I, however, found in 

 Myopotamus an artery supplying the surface of the pyriform lobe, 

 siich as exists in Chinchilla and Lag ostomies, and rising just 

 behind the middle cerebral. The anterior cerebral is more 

 symmetrical than in those Rodents. Each divides into two equal 

 branches not far from its origin : of these the outer runs along 

 the olfactory region of the lower surface of the hemispheres ; the 

 inner joins the corresponding branch of the opposite side, becomes 

 the single callosal artery, and before it reaches the surface of the 

 corpus caUosum again divides into two. 



Hyrax capensis. — The arteries at the base of the brain of Hyrax 

 show certain differences from those of other mammals referred to 



Text-fie'. 18. 



Base of brain of Hyrax capensis. 



ca., carotid artery ; ce., junction of middle and anterior cerebrals ; 

 op., ophthalmic arteries. 



in the present communication. A noteworthy point is the great 

 length of the basilar artery, the point of formation of which from 



