31.2 DR. G. ELLIOT SMITH ON 



be more richly fuiTowed even than that of llyrmecophaga. We know that the pallium 

 increases in extent in any order with the added hulk of the animal. A Carnivore as 

 small as Cyclottirus would have a pallintu with as complex a pattern as the Great 

 Ant-eater. 



I have not had an opportunity of examining- the brain of the small arboreal Ant-eater 

 Cycloturus, Init, judging- from the figures of Tiedemann, Pouchet, and Gervais, its 

 pallium must be quite smooth and devoid of sulci. The transition from Tamandua with 

 its shallow and faintly-marked sulci to the smooth condition is quite simple, and amply 

 justified by the difference in size between these two Ant-eaters. 



One cannot fail to be struck by the resemblance in the configuration of the hemisphere 

 of Tamaiidna, and especially Cijdoturus, to the Rodent type. Moreover, the exact 

 shape of the corpus callosum and the behaviour of the hippocampal formation, which we 

 liave found so variable elsewhere, are closely reproduced in the Uodentia. When we 

 compare the brain in the Rodeutia with that of the Myrmecophagidse, we can confidently 

 afiirm that any superiority of type that may exist certainly does not favour the Rodent. 

 Unfortunately no collection of brain-weights is available for comparing the two 

 groups on the basis of relative size of brain. The solitary brain-weight of Tamandua 

 which Max Weber gives* is much highei- than tliat of any Rodent of approximately 

 the same body-weight. But a large mass of data is necessary before we can confidently 

 compare the two groups. 



It is sufficient at present to note that there is an interesting series of transition stages 

 in pallial modification in the Carnivora, Myrmecophagida;, and Rodentia. But while 

 the evidence at our disposal conclusively shows the distinct superiority in cerebral 

 organization of the Carnivore over the Ant-eater, it does not permit us to say that the 

 latter is in any way infei-ior to the Rodent. 



All the information we possess clearly and decisively points to the undoubted kinship 

 of the Ant-eaters with the Sloths and Armadillos. But for several reasons I propose 

 to consider next the pallium of the Aard-vark. From the writings of Pouchet and 

 Gervais one might conclude that there is a close resemblance between the brains of 

 Mynnecojihaga and Orycteropas. I shall demonstrate that such a belief is utterly 

 illusory and erroneous, and. shall discuss Orycteropzis in this place in order to show the 

 strong contrast between the two forms, and in tliis way to accentuate the im])ortance of 

 the agreement we have found between Mynnecophaga and the Carnivora. 



In our brief review of the literature relating to the brain in different families of 

 Edentata, Ave found that practically nothing was known of the brain in the Orycteropidaj 

 beyond its general shape. Leuret published some observations t upon the brain of 

 Oi-ycteropm sixty years ago, but, acting under the mistaken idea that mammals might 

 be classified according to the relative richness of their cerebral convolutions, he included 

 in one group three such dissimilar brains as those of Orycteropus, Macropus, and 

 Pteropus, without giving us any information of lasting value. 



* Max Weber, op. cit., Gegeubaur's ' Fe.st.schrit't,' lS9t5. 



t Leuret, ' Anatomie com2)aree du Systume nerveux,' Paris, 1838. 



