190 ME. F. E. BEDDARD ON THE ARTERIES [Feb. 2, 



large as t find * them to be in the following Carnivora : — Felis 

 tigris, F. leo, Viverra civetta, Ursus syriacus, Arctictis hinturongy 

 Ganis occideoitalis, Galictis harhara, Genetta pardina, Suricata 

 tetradactyla, and Herpestes auro2nmciaUis. In view of conflicting 

 opinion as to the aflinities of Edentates we cannot, I think, afibrd 

 to neglect even the smallest indications. 



I may further point out that in the Carnivoia generally, so far 

 as my expei'ience allows me to state, the vertebral arteries enter 

 at the middle of the rhomboid formed by their union with the 

 anterior spinal. It is not the case, however, with Galictis, which 

 in this feature comes nearer to Tainandua than does any other 

 carnivore. 



Immediately after the division of the basilar artery anteriorly 

 to form the cu'cle of Willis, and behind the third nerves, two 

 arteries are given off on each side, and on the right side a third 

 which is represented by a small twig only on the left. They all 

 arise at appreciable distances from each other. The number is 

 obviously unusual ; but, so far as I can ascertain, all these arteries 

 are cerebellar. In front of the third nerve arises the posterior 

 cerebral. Owing to the considerable antero-posterior length of 

 the circle of Willis, this artery is very greatly in advance of the 

 bifurcation of the basilar artery, and yet well behind the level of 

 the entrance of the carotids into the circle. 



That poi-tion of the brain-surface which lies within the circle 

 of Willis, behind the origin of the posteiior cerebral arteries, is 

 covered with a plexus of blood-vessels dei-ived from the anterior 

 side of the posterioi- arteiial ti'unk which forms the circle of 

 Willis. I have observed a similar plexus in a Gazelle {Gazella 

 nififrons), but hardly venture to bring this fact forward as 

 evidence of Ungulate affinity in the brain of Tamandua. The 

 carotids are moi-e slender than the circle of Willis into which they 

 debouch. About halfway between this point, which, as will be seen 

 from the drawing (text-fig. 19, p. 189), is about on a level with the 

 infundibulum, and the optic nerves is given off on either side 

 the middle cerebral artery. The circle of Willis is completed 

 anteriorly in a way often found among mammals, the junction 

 being effected before the single artery derived therefrom is lost to 

 sight in the interhemispheral sulcus. 



The cerebral arterial system of Tragulus meminna presents 

 certain peculiarities of its own (text-fig. 20, p. 191). Concerning 

 the basilar arteiy and its lateral branches, there are at least two 

 important facts to be noticed. In the first place, the middle 

 cerebellar artery, so unimportant as a soiu-ce of cerebellar blood- 

 supply in such Rodents as I have studied, is fuU}^ equal in size to 

 the anterior cerebellar artery, and can be easily ti^aced into its 

 ramifications over the posterior half of the cereloellum. It gives 

 off on the way important branches to the roots of the fifth and 

 seventh and eighth nerves. The second and striking fact about 



* Loc. cit. p. 775, woodcut, fig. III. 



