192 MR. F, E. BEDDARD ON THE ARTERIES [Feb. 2, 



first between the cerebrum and the cei'ebellum. It is remai-kable 

 that from the most posterioi-ly situated of these branches a 

 considerable twig goes to the cerebellum. 



The circle of Willis has an hourglass-shaped outline like that 

 in Bos taurus as figured by Tandler*. But the "waist" of the 

 hourglass, though marking the exit of the ophthalmic t, is opposite 

 to the pituitary body and well behind the origin of the middle 

 cerebral aitery. The circle of Willis gives off near to the origin of 

 the middle and antei'ior cerebrals a branch on each side to the 

 pyriform lobe, concerning the existence of which in the Rodentia 

 mention has already been made. The nature of the anterior 

 cerebral arteries is somewhat remarkable. On the left side this 

 ai'tery runs forward and curves over the corpus callosum in 

 the usual way. As it bends over it gives off a branch running 

 upwards which bifurcates ; fi-om the point of bifurcation a twig 

 reaches the light anterior cei-ebral, or rather a more slender 

 artery running above the left anterior cerebral but not connected 

 with it except as just stated, which seems to me to be the olfactory 

 branch only of the light cerebral. I am inclined, in fact, to look 

 upon the right anterior cerebral as missing and as being repi-e- 

 sented by the olfactory branch of that artery only. In this case 

 the anterioi- connection between branches of the right and left 

 anterior cerebiuls will not be the equivalent of the anterior 

 communicating arteiy of other mammals. Finall}^, I may call 

 attention to a small artery (text-fig. 21, A, h, p. 194) which runs 

 fi'om the middle cei-ebral artery to the anterior cerebral aiteiy of 

 the left side. 



Carnivora. — I have examined a considerable numbei- of bi-ains 

 belonging to this order of mammals, which I shall not describe in 

 detail, but concerning which I shall attempt some generalities. 

 A most charactei'istic feature of the Carnivoi'a, seen also in the 

 Seal (according to Dr. Tandler's figure +), is the large size not 

 only of the vertebral arteries but of the anterior spinal. The 

 latter arises, as in Man, &c., by a branch from each vertebral, 

 which speedily unite to form a single trunk running along the 

 anterior face of the spinal cord. The result is a strong rhom- 

 boidal-shaped vessel from the lateral angles of which arise the 

 vertebrals. As a rule, that is to say, their origin is from the 

 latei'al angle of this " circle," but, as already stated, in Gcdictis 

 they lie much farther back close to the junction of the two 

 " roots" of the anterior spinal artery. 



In these features the Carnivora contrast with such other 

 mammals as I have examined, the only type resembling them 

 being, as I have already said, Tamandua. So far as my experience 

 goes, the ophthalmic artery generally arises from the circle of Willis 

 anteriorly to the entrance into that circle of the carotid, and in 

 Ictonyx quite at the anterior " coi'ner," where the middle and 



* Loc. cit. p. 775. 



t I presume this artery to be the ophthalmic. 



X Loc. cit. pi. V. tig. 19. 



