254 PHYSIOLOGICAL SERIES. 



The orbital sulcus is very small, and placed so far 

 forward on the apex of the hemisphere that it is hidden by 

 the olfactory bulb, and is believed by many writers (e. </., 

 Ziehen, Arch. f. Psych. 1896) to be absent. 



The deepest sulcus on the hemisphere is the suprasylvian 

 which extends backward above, but without joining the 

 vertical postsylvian (compare fig. 125). 



Holl (op. cii. p. 238) considers that no Sylvian fissure is 

 present, but we can have little hesitation in regarding the 

 sulcus which springs from the junction of the deep anterior 

 rhinal and the shallow post-rhinal fissures as the pseudo- 

 sylvian sulcus. After a short oblique course upward and 

 slightly backward, it joins the posterior ectosylvian which 



Fig. 125. (Nat. size.) 



SULC.SUPRAS. SULC.ENT.LAT. 

 SULC. CPU. j SULC.LAT. / 



SULC.P.SYL. 



RHIM - F< SULC.ECTOS.P. 



pursues a short course upward and forward and is then 

 joined to the anterior ectosylvian sulcus (compare Roll's 

 figure of Herpestes ichneumon). 



The lateral sulcus is apparently fused to an ansate 

 element in front, but is not joined to the small oblique 

 coronal sulcus. 



The shallow postlateral is prolonged forward as a 

 fragmentary entolateral sulcus. 0. C. 1325 i c. 



Holl, Arch. f. Anat. u. Entwick. 189y, p. 238. 

 Mivart, Journ. Linn. Soc., vol. xix. 1886, p. 7. 

 [Since this account was written I have examined the 

 brains of two specimens of Herpestes ichneumon, and the 

 interesting variations in these four hemispheres decisively 

 .-how that the real nature of the sulci in question accords 

 with the suggestions in the accounts already given. 



