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Show 192 MR. F. E. BEDDARD ON THE ARTERIES [Feb. 2, first between the cerebrum and the cerebellum. It is remarkable that from the most posteriorly situated of these branches a considerable twig goes to the cerebellum. The circle of Willis has an hourglass-shaped outline like that in Bos taunts as figured by Tandler *. But tlxe " waist " of the lxoux-glass, though marking the exit of the ophthalmic t, is opposite to the pituitary body and well behind the origin of the middle cerebral artery. The circle of Willis gives off near to the origin of the middle and anterior cerebi-als a bx-anch on each side to the pyx-ifoi'm lobe, concerning the existence of which in the Rodentia mention has already been made. Tlxe nature of the anterior cerebral arteries is somewhat remarkable. On the left side this artery 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; from tlxe point of bifurcation a twig reaches the right anterior cerebral, or rather a more slender artery running above the left anterior cerebral but not connected with it except as just stated, which seems to m e to be the olfactory branch only of the right cerebral. I a m inclined, in fact, to look upon the right anterior cex-ebx-al as missing and as being represented by the olfactory branch of that artery only. In this case tlxe anterior conrrection between branches of the right and left anterior cerebrals will not be the equivalent of the anterior-communicating artery of other mammals. Finally, I may call attention to a small ax-tery (text-fig. 21, A, b, p. 194) which runs from the middle cerebral artery to the anterior cerebral artery of the left side. Carnivora.-I have examined a considerable number of brains belonging to this order of mammals, which I shall not describe in detail, but concerning which I shall attempt some generalities. A most characteristic feature of the Carnivora, 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 lateral angle of this " circle," but, as already stated, in Galictis they lie much fax-ther 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 m y 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 " corner," where the middle and * Loe. cit. p. 775. f I presume this artery to be the ophthalmic. X Loc. cit. pi. v. fig. 19. |