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Show 194 MR. F. E. BEDDARD ON THE ARTERIES [Feb. 2, the internal face of the hemispheres as does the main trunk of the anterior cerebral in Man. In addition to these, a single artery from tlxe left side, arising from the olfactory just after the point where the middle cerebral is given off, approaches and appears to go in tlxe median interhemispheral arteries. The only other brains among the many which I have examined which seem to agree with that of Betlongict are those of a Ground-Squirrel (Xerus erythropus) and of the Viscacha (Lctgostomus trichodactylus). In the latter, however, I could find only one of the paix-ed vessels arising far forward along the olfactoxies and helping to constitute tlxe median interhemispheral callosal ; and in the former I could not find eithex- of them. In both, the single inner branch of the anterior cerebral arises from the left side. That it does so in specimens of three species selected at random appears to argue that the condition of asymmetry is normal. Text-fig. 21. Anterior cerebral system of (A) Tragidus meminna ; (B) Viverra civetta; and (C) Gazella rvfifrons. a., rudimentary callosal of right side (?); ac, anterior communicating artery; b., branch connecting middle and anterior cerebrals; ca., callosal artery; me., middle cerebral; o., olfactory. The human type of arterial distribution is to be seen in the Carnivora, that is to say in the JSluroid division of that order. In Viverra civetta * (see text-fig. 21, B ) tlxe only differences fx-onx * Tandler (loc. cit. Taf. iv. fig. 13) does not figure the anterior communicating artery, but states it to be present. 1 can confirm his statement. |
