204 



below, have hitherto been published, simply because it has never 

 occurred to me to question the olfactory nature of the tuberculum 

 olfactorium. 



The passage of fibres from the tractus olfactorius (not the mesial 

 olfactory root, as Calleja and others imagined) into the cortex of 

 the tuberculum olfactorium is visible to the naked eye in many of the 

 larger macrosmatic mammals, but I have never seen this tract so 

 obtrusively shown as it was in the fresh brain of an Orycteropus 

 aethiopicus, which died in the Giza Zoological Gardens about three 



— Bulbus olfactorius 



Tractus bulbo-tuberc. 



Pedunculus olfactorius — 



Tuberculum olfactorium 



Locus perforatus 



Chiasma optic. 



Lobus pyriformis 



— y— A — Tractus olfactorius 



—>*/,V- Tuber, tract, olf. 



Fig. 1. Diagram representing the ventral surface of the anterior pai-t of the left 

 cerebral hemisphere of Orycteropus aethiopicus SuNDEV. 



years ago, and for which I am greatly indebted to Captain Flower, 

 the Director of the Gardens. 



The general features of the brain of the Aard-vark I have de- 

 scribed in considerable detail ^). The special peculiarities of the Giza 

 specimen are shown in the accompanying diagram (Fig, 1), representing 

 the ventral aspect of the anterior half of the left hemisphere. Emerging 

 from the bulbus olfactorius on the ventral surface of the pedunculus 

 is the large tractus olfactorius, the caudal end of which is seen ending 

 at the tuberculum tractus. The greater part of the tract, however, is 



1) The Brain in the Edentata. Transactions of the Linnean Society 

 of London, 1898, p. 287. 



