382 DE. G. ELLIOT SMITH ON 



weight possess a much heavier braiii. We have unfortunately ojily a single record of the 

 brain-wciglit in Tmnandua : — a Tamandiia tctradactyla, 2 , weighing 1168 gr., has a brain 

 of 17'35 gr.* This is an extremely higli brain-weight for an animal of this size, far 

 exceeclii]g that of any of the E-odentia, Chiroptera, or Marsupialia of similar size, although 

 it is still much below the Carnivore. Max Weber, who is extremely careful in stating 

 when liis measurements refer to young animals, makes no comment upon this measure- 

 ment. His specimen, if not young, is apparently very small for a Tamandua, its body- 

 length {without the tail) being only 37 cm. Dr. Sclater gives f the corresponding 

 measurement of a Tamandua which was in the Zoological Gardens as 20 inches (about 

 50 cm.). Rengger gives the length of a TamandiM which is still larger than Sclater's 

 specimen, being 22 inches (about 55 cm.) long %. Bu.t even admitting that Weber's 

 measurement refers to a young animal, the brain-weight which he records would be con- 

 sidered large even for an animal of the dimensions of Eengger's specimen. Por even then 

 the l)rain would be relatively larger than that of many Eodents of a corresponding size. 

 When we recall the fact that the brain of Tamandiia is not unlike that of a Rodent, 

 and may therefore be legitimately compared with it, we must admit that the brain of the 

 Ajit-eater is at least as highly developed as that of the Rodent. 



We have unfortunately no record of the brain-weight in Cycloturus, although 

 Pouchet § assures us that the brain of this small Ant-eater (which he calls Dionyx) is 

 much lai'ger than that of Rodents and Insectivores || of a similar size. 



Taking all tliese facts into consideration, Ave are safe in concluding that the Ant-eaters 

 are equijiped with brains which, so far as size is concerned, are certainly not inferior to 

 those of Rodents, and in all probability show a decided superiority. 



According to Flechsig, the " centres of association " are as yet small in Carnivores, 

 while in Rodents they are entirely wanting. This statement may be interpreted to 

 mean that the insidious growth of association-elements within the pallium is not yet 

 sufficiently great in Rodents to make itself manifest, but that it has ncreased to such 

 an extent in Carnivores as to be recognizable beyond the limits of the areas of pro- 

 jection. It is in the highest degree probable that the distinction between the pallium in 

 MyrmecopJiaga and a Dog of a corresponding size is wholly due to the more abundant 

 development of association-elements in the Carnivore. For we have no reason to believe 

 that any of the sensory areas of the Ant-eater are to any marked degree less rich in 

 sensory elements than they are in the Dog. Nor are the primary end-stations, such as 

 the corpora geniculata, the corpora qnadrigemina, the tubercida acustica, or any other 

 of the masses of grey matter from which sensory tracts may arise and proceed to the 

 pallium, any smaller in the Ant-eater than they are in the Dog. In other words, so far 

 as we can judge, the pallium of the Ant-eater is as abundantly supplied with sensory 

 tracts as is the jJallium of the Dog, and therefore we are, I think, justified in concluding 



* Max Weber, op. cit., Gegenbaur's Festschr. j). 7. t P. L. Sclater, Proc. ZooL Soc. London, 1871, p. 540. 



X Eengger, ' Naturgeschichte der Saugethiere von Paraguay,' Basel, 1830, j). 309. 



§ Pouchet, po. cit., tm. v. p. 664. 



II He says Carnivores, but from the context there can be no doubt that he means Insectivores. 



