300 DR. G. ELLIOT SMITH ON 



{op. cit.) have alroady called attention as resulting from the upAvard projection of the 

 bony semicircular canals in the periotic hone. Pouchet has already given a ligure of tlie 

 ventral surface of the brain, which indicates tlie situation of this depi'ession. 



The imperfect descriptions of the brain of Manis which Pouchet {op. cit.) and Gervais 

 {op. cit.) had given have recently been supplemented by the concise and well-illustrated 

 description by Mas Weber {op. cit.). I have been able to confirm the accuracy of his 

 brief description by the examination of two specimens of this genu.s. The basal regions 

 of the hemisphere present in a typical manner the characteristic features which we have 

 met in all the other forms. The base of the brain is very broad. The large olfactory 

 bulb forms a thick buffer-like pad upon the flattened ceplialic extremity of the 

 hemisj^here. The large tuberculum olfactorium presents an almost circular outline. 

 The posterior part of the pyriform lobe is most markedly dependent, and descends to a 

 much lower level than the rest of the hemisphere. This feature is much more pro- 

 noimced than it is in any other individual in this heterogeneous group of mammals, and 

 is probably a result of the obvious restriction to tin: expausiou of the brain in the longi- 

 tudinal direction. 



The rhinal fissure is interrupted in a manner which suggests an analogy to the 

 arrangement in the Armadillos. Tiiere is a very short horizontal anterior rhinal fissure, 

 which is quite independent of the posterior rhinal fissure. The latter begins at the 

 posterior margin of the hemisphere and arches forward, but just before reaching the 

 anterior rhinal fissure it extends up\^ard into continuity with a pallial fissure, in a manner 

 not unlike the posterior rhinal fissure in Dasyj^us. 



The fundamental features of the regions of the base of the brain which we have just been 

 considering vary within relatively narrow limits in the Mammalia, although both Mono- 

 tremes exhibit features in common which readilv distino;uish them from all other 

 mammals. Such variations as we have found among the different representatives of this 

 order are characteristic of the changes which the basal region of the hemisphere undergoes 

 in the wider range of the Mammalia generally, and are in the main associated witli the 

 habits of life rather than witli the systemic position of the individuals. For we find 

 among other mammalian orders, more especially the Marsuj)ialia, Insectivora, Kodentia, 

 Carnivora, and Ungulata, parallel modifications Avhich indicate the more or less direct 

 causal relationship to the mode of life. All the areas which we have been considering 

 are intimately associated with the olfactory apparatus, and, Avhatever other functions 

 they may subserve, there can be no question that tlieir predominant r61e is to constitute 

 a receptive area for incoming impulses of smell. The importance of the sense of 

 smell varies considerably in the different members of this order, although in all it reaches 

 a very high degree of acuteness, as the great development of the olfactory bulb and its 

 associated cortical areas demonstrates. But in this macrosmatism the Edentata are like all 

 other lowly-organized mammals, in which the sense of smell has a larger function 

 than in higher mammals, in which an intelligence dispenses with the necessity of any 

 such predominant and guiding sense as the impressions of smell convey. 



In Edentates like (Jvycteropus and the Dasypodiilce, which S])end their Jives mainly in 

 digging and bru-roA^iug in the ground foi' t)bjects as to the position of which the sense of 



