NERVOUS SYSTEM. VERTEBRATA. 321 



almost so in the Camels, Giraffe, Dicotyles, and Pig/' as 

 they are also on the left hemisphere of this specimen. The 

 common occurrence of this phenomenon in other Orders 

 indicates the probability of its being a primitive character. 



The suprasylvian sulcus is represented by a relatively 

 short transverse arc which is separated from the postsylvian 

 sulcus by an oblique sulcus (fig. 185, E). There is a well- 

 defined entolateral sulcus. There is also a complete cingular 

 arc, as in ihe Horse and the Tapir. 



" Looked at generally, the brain of the Hippopotamus is 

 evidently very different from that of the genus Sus and 

 its nearest allies. In the great breadth and complicatedness 

 of the [third arcuate gyms of Leuret] it most resembles 

 the Camels and the Giraffe, from the form of which it 

 strikingly differs in the much less ' pronation ' [inward 

 rotation] of the hemisphere. On the whole, it stands very 

 much by itself (Garrod). 0. C. 1328 L a. 



Garrod, Trans. Zool. Soc., vol. xi. 1879, p. 16. 



D. 419. A cast of the cranial cavity of a Hippopotamus (Hippo- 

 potamus amphibius) . 



Family GAMELID^E. 



D. 420. The brain of an Arabian Camel (Camelus dromedarius) . 

 In general appearance and size the brain of the Camel 

 resembles that of the Horse ; and this resemblance is also 

 found to obtain to a very considerable extent in the arrange- 

 ment of the sulci of the cerebral hemisphere. The anterior 

 rhinal fissure has disappeared except in its most posterior 

 part, but nevertheless the line of demarcation between 

 pyriform lobe and neopallium is quite obvious. The 

 posterior rhinal fissure is also exceedingly shallow and is 

 not joined to the anterior rhinal. 



The posterior end of the anterior rhinal fissure is very 

 deep and is prolonged upward and backward for a short 

 distance in the neopalliuai as the posterior limiting sulcus 

 of the Sylvian depression : this depression is partially 

 overlapped above by an operculum, the horizontal limiting 

 sulcus of which is parallel to the rhinal fissure. This 

 VOL. ii. y 



