NERVOUS SYSTEM. VERTEBRATA. 307 



D. 392. A cast of the cranial cavity of an Indian Elephant 

 (Elephas indicus). 



This shows that the enormous brain of the Elephant has 

 very much the same form as that of the Yak (Poephagus 

 grunniens), but the caudal broadening and the frontal 

 narrowing of the hemispheres is much exaggerated. 



Extinct Suborder TYPOTHERIA. 



D. 393. A cast of the cranial cavity of Typotlwrium cristatum. 



In this cast the horizontal rhinal fissure of the Ungulates 

 can be recognised. There is a deep impression in the 

 " Sylvian region/' produced apparently by a suprasylvian 

 sulcus, analogous to that of Myrmecopliaga, and the hemi- 

 spheres are considerably expanded behind it. As a whole, 

 the brain is not unlike that of a Chevrotain. 



It has a small rounded cerebellum such as Procavia and 

 Hydrochcerus present. 



Gervais, Journ. de Zool., t. i. 1872, p. 430. 



Elephant's brain [fig. 174]) is separated from the irregularly Y~ sna P e d post- 

 sylvian sulcus by an oblique sulcus (fig. 185, E), in a manner similar to the 

 separation of the sulcus B in the Elephant from the long, oblique, Y~ sn aped 

 postsylvian by the sulci E and F (fig. 174). The lateral and entolateral sulci 

 become exceedingly irregular in many Ungulates (compare the Tapir's brain, 

 fig. 180) by the development of accessory branches, and in the Elephant 

 the continuity of the main sulcus becomes broken, so that instead of a long, 

 well-defined, lateral and entolateral sulcus, we find a very complicated pattern 

 formed by short, deep, irregular sulci. In the Tapir the coronal sulcus 

 (fig. 180) has become so much shifted from the sagittal direction, which it 

 usually has in the Ungulata, that it is more nearly transverse. In the 

 Hippopotamus the main coronal sulcus is still sagittal (fig. 186), but it is 

 provided with numerous transverse rami. In addition there is in this brain 

 a transverse sulcus (figs. 185 & 186, c) parallel to and compensatory to the 

 suprasylvian sulcus. In the Elephant's brain we find in the region where 

 we should seek for the coronal sulcus no trace of any sagittally directed 

 furrows, but there are two deep transverse sulci (figs. 174 & 176, c & H), 

 which must be regarded as representatives of the coronal sulcus of the Tapir 

 and the sulcus c of the Hippopotamus respectively. Between the sulcus c 

 and the orbital sulcus there is a deep, long, paraorbital sulcus, such as we 

 find in almost all Ungulates. 



