194 



MR. F. E. BEDDARD ON THE ARTERIES 



[Feb. 2, 



the intei'nal face of the hemispheres as does the main trunk of the 

 anterior cerebral in Man. 



In addition to these, a single artery from the left side, 

 arising from the olfactory just after the point where the middle 

 cerebral is given off, approaches and appears to go in the median 

 iiiterhemispheral arteries. The only other brains among the 

 many which I have examined which seem to agree with that of 

 Bettongia are those of a Ground-Squirrel {^Xerus erytliropus) and 

 of the Yiscacha {Lagostomus tricliodactyhhs). In the latter, how- 

 ever, I could find only one of the paired vessels arising far forward 

 along the olfactories and helping to constitute the median inter- 

 hemispheral callosal ; and in the foi-mer I covdd not find either 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 

 asymmetiy is normal. 



Text-fig. 21. 



Anterior cerebral system of (A) Tragttlus meminna ; (B) Viverra civet fa: 

 and (C) Gazella riififrons. 



«., rudimentarj' callosal of right side (?) ; ac, anterior communicating arterj- ; 

 h., branch connecting middle and anterior cerebrals ; ca., callosal artery; 

 inc., middle cerebral ; o.. olfactory. 



The human type of arterial distribvition is to be seen in the 

 Carnivora, that is to say in the ^luroid division of that oi'der. 

 In Viverra civetta * (see text-fig. 21, B) the only differences from 



* Tandler {loc. cit. Taf. iv. fig. 13) does not figure the anterior communicating 

 artery, but states it to be present. I can confirm his statement. 



