108 MK. F. E. 13EDDARD ON THE [Feb. 7, 



thus formed. These are the rather strongly developed olfactory 

 arteries, which meet but do not join in the median intracerebral 

 fissure, along which they run towards the olfactory bulbs. 



The brain of Asio mexicanus shows no differences, except in the 

 merest minutise. 



Text-fie-. 17. 



Braiu of Pelecanusfuscus (ventral asx^ect), showing the principal branches 

 of the arterial system. 



Lettering as in text-fig. 15. 



Aquila verrecmxi. — The bi-ain of this bird shows the more general 

 avian asymmetry in some of its arteries. Thus the anterior spinal, 

 which is double for some distance, enters the left cerebellar artery 

 instead of being dii^ectly continuous with the basilar trunk. The 

 basilar artery, moreover, is connected with the light carotid only, 

 or if with the left also l)y a quite minute ti'unk, which I have not 



