THE BRAIN IN THE EDENTATA. 



289 



the large cavity or ventricle of the bulb we find a very prominent longitudinal ridge in 

 the floor, Avhich is tlie result of this indentation (fig. 19), 



The olfactory bulb is connected with the rest of the licmisphere by a large rounded 

 peduncle, which is visible upon the base of the brain in the interval between the 

 tuberculum olfactorium and the buJbus olfactorms. Even in a view of the dorsal aspect 

 of the brain the peduncle is visible, because the apes of the cerebral cortex does not 

 overhxp it to so great an extent as in most mammals. On the lateral aspect of the 

 hemisphere the massive olfactory peduncle extends backward and becomes directly 

 continuous with the cephaUc extremity of the j^yriform lobe. The medullary covering 

 which whitens the surface of the peduncle converges to form the compact olfactory tract, 

 and immediately above this we find- the vermiform anterior pyriform lobe. The narrow 



Fi-. 3. 



■ - bulb, olfact. 

 —ped. olfact. 



-lob. pyriform. ant. 

 tisa. rhinal. 



. fiss. prima 

 — area A 

 '-^ area B 

 ■■ area C 

 fis3. Beeunda 



medulla oblong. 



Doreiil surfuci-^ oi' ))raiii of Orjjcteropus. Nat. size. 

 Based on a pencil sketch by tlie late Rt. Hon. T. H. Huxley. 



band of grey substance which constitutes this part of the pyriform lobe is deeply 

 constricted in many places, so that it appears to consist of a series of round knolis. 

 These knobs are so prominent that they produce correspondingly deep depressions on the 

 cranial wall, and hence we can readily recognize them in cranial casts. A beautiful 



