106 



MR. F. E. BEBDARD ON THE 



[Feb. 7, 



connected with both carotids, and thus the circle of Willis is com- 

 Y-)leted posteriorly. Nevertheless there still remains an asymmetiy 

 ill that the two posterior commvmicating arteries are of uneqiial 

 size. The right artery, in fact, is more than twice the diameter 



Text-fig. 16. 



Brain of Ara htjacinth'ma (ventral aspect), showing the princiijal branches 

 of the arterial system. 



Car. Carotids ; other lettering as in text-fig. 15. 



of the left. In both cases the postei'ior communicating artery 

 gives off the artery to the optic lobe of its side before joining the 



