NERVOUS SYSTEM. VERTEBRATA. 



309 



The features of the olfactory bulb, tuberculum olfac- 

 toritmi, and pyriform lobe are also shown very clearly. 

 The arrangement of the rhinal fissure, which separates the 

 latter from the neopallium, is peculiar. The anterior and 

 posterior rhinal fissures do not join (fig. 179), and appear 

 to pursue a very considerable course parallel to one another 

 in such a manner that the forward extension of the pos- 

 terior rhinal fissure lies in the neopallium (and may be 

 joined to the orbital sulcus), and the caudal extension of 

 the anterior rhinal fissure lies in the pyriform lobe. This 

 arrangement may be compared to that found in the Aard- 

 vark. 



The furrow usually called " Sylvian fissure " in the 

 Ungulata cannot be strictly regarded as the exact repre- 



Fig. 179. (xf.) 



SULC . LAT. 



FLOC 



SULC.OR& 



RHIN.F. 



sentative o any of the various forms of " Sylvian fissure " 

 (so-called) of the Carnivora nor of the true (Primate) Sylvian 

 fissure. It may be caused by factors analogous to those 

 which produce the similarly-named " fissure " in the 

 Carnivora, and hence it is convenient to retain the name ; 

 but only with the distinct reservation that no strict 

 homology is thereby implied. Holl has shown that the 

 sulcus usually called " Sylvian " in the Ungulata more nearly 

 represents a complex of two sulci, representing the ecto- 

 sylvian of Carnivores, the so-called " Sylvian fissure " of the 

 Carnivore being represented by a very insignificant furrow. 

 But I have here retained the conventional nomenclature. 



