286 



PHYSIOLOGICAL SERIES. 



will bo noticed in the latter that the first arcuate gyru< ha< 

 been completely submerged in the " Sylvian fissure." and 

 i lure is a strongly-marked tendency for the anterior limb 

 of the second arcuate gyms to sink into the same gn-ai 

 gulf. In some Bears and in the Badger this may actually 

 occur. And in Otaria and the Seals the tendency become- 

 more distinctly pronounced ; in other words, the anterior 

 limb of the second arcuate gyrus becomes depressed and 

 partially overlapped by the third arcuate gyrus. A 

 result we find a great vertical depression on the lateral 

 .aspect of the brain (fig. 161) in which the " Ursine Sylvian 



Fig. 161. 



SULC SUPRAS. 

 SULC.LAT. 



SULC.ANS.MIN. \ 



SULCI ANS. 



SULC. COR.... 

 SULC.CRU. 



r 



SULC.PRECRU. 



SULC. SUPRAS. 



SULC P.SYL. 



\ SULC PLAT 



SULC.URS. 



fissure" and the suprasylvian sulcus are seen separated by 

 a narrow strip of submerged second arcuate gyrus. The 

 suprasylvian sulcus emerges from the apex of this great 

 depression and, after giving off a minor ansate suleu-. 

 ceeds obliquely upward and backward to end between the 

 two pieces of the forked upper end of the postsylvian 

 (posterior suprasylvian) sulcus. This Sylvio-suprasylvian 

 complex may be regarded as analogous to the Sylvian 

 fissure of Human Anatomy (vide infra). 



The postsylvian sulcus is not joined to the suprasylvian 

 (figs. 161 & 162) ; its lower extremity bends forward 

 (fig. 161) almost as far as the Sylvian fissure. Several 



