442 



PHYSIOLOGICAL SERIES. 



so closely that he can sec at a glance how far the rhinal 

 fissure and the pyriform lobe extend (figs. 249 and 250). 



There is a deep vallecula Sylvii, which leads into the 

 stem of the Sylvian fissure. The latter is clearly formed in 

 this interesting specimen by the meeting of two definite 

 opercula, temporal and orbital respectively, as in the human 

 brain. As these opercula extend laterally they diverge 



Fig. 249. (x |.) 



SULC.SUP. LIM 



from one another so as to expose a small triangular de- 

 pressed area of insula (fig. 250;. In this specimen one can 

 see at a glance that the fronto-orbital sulcus (the anterior lip 

 of which is so markedly opercular) is really the anterior 

 limiting sulcus of the insula. And the dorsal open-iilum 

 is also so complete that the forward prolongation of the 

 superior limiting (Marchand's " opercular ") sulcus appears 

 to join the anterior limiting sulcus *. That this close 

 resemblance to the human condition is not the rule in the 



It is interesting to note that the superior limiting sulcus does not 

 actually join the fronto-orbital even in this extreme case, the two sulci b- in^r 

 separated by a submerged gyrus. Thus we cannot speak of anterior limbs 

 of the Sylvian fissure in the Anthropoids. 



