296 



DR. G. ELLIOT SMITH ON 



as it is in the younger Bradjipiis. The anterior rhinal fissure is very ohlique, hut the 

 posterior rhinal fissure is almost horizontal (tig. 12). 



The conformation of the base of the brain in the Bradypodidce is so like that of 

 Tamandua that it is unnecessary to give special illustrations, nor is it requisite to describe 

 these features in detail. The general shape of the base of the brain in Brady pus is very 



bulb, olfaot. 



tnbercnl. 

 olfact. 



fiss. rhinal, paraflooc. 

 lob. pyriform. 



Lateral surface of brain of lii-ddiiiinn ilnlitclijlus. Nat. size. 



bulb, olfact... 



fisa. rhinal. 



paraBocc. dors. 



. paraflooc. ventr. 



tract, olfact 



• nerv.V. 



■ lob. pyriform. 

 tnbercoL olfact. 



: flocculns 



pons Varol. 



trapeziom 

 . pyramid. 



Lateral surface of Imiin of CholceiiHs didactj/lvs-. Slif;htly enlarged. 



much like that of Tamcmdua (fig. 9), but in the former more of the pallium is visible along 

 the lateral margin of the anterior part of the pyriform than is the case in the Ant-eater. 

 This means that the proportion of pyriform lobe to iiallium is less in the Sloth than in the 

 partially arboreal Ant-eater. In Cholcepns the base of the brain appears to be relatively 

 broader than it is in B)-adijpns, but otherwise it presents a close resemblance. 



In none of the Armadillos (with the possilile exception of Priodon) do we find a 

 complete rhinal fissure. Nothing is known of the brain of Priodon, except such 

 information as we can gather from the examination of cranial casts, such as Gervais has 

 represented {op. cit. pi. ii. fig. 12). But it is quite possible and even probable that in 

 such a large brain a complete rhinal fissure will be found, because we find among 

 mammals that an increase in bodily dimensions is accompanied by an increased extent 



