340 



DE. G. ELLIOT SMITH ON 



Forbes has given tis an exceedingly crude scheme of the dorsal aspect of one hemisphere 

 of Tamandita *. My own observations were made upon these brains, one of which had 

 been left to the lloyal College of Science by Professor Huxley, aud the other two are 

 at present in the galleries of the Eoyal College of Surgeons. To illustrate ray description 

 I have constructed a semischematic drawing (fig. 8) from one of the specimens in the 

 Collesje of Surgeons. 



If we imagine an extension of the process of simplification which would be necessary 

 to reduce the brain of Canis to the condition of Iliirmecopliaga, so that in a smaller 

 braiu all the less pronounced features in the brain of the latter became eliminated, and 

 the more deeply-impressed characters became more faintly marked, we should gain some 

 idea of the appearance of the brain of Tamandna . We have seen that in Ca)iis the 

 faintly-marked lips which serve to denote the boundaries of the fossa Sylvii of Jlyrmeco- 

 2)liaga have become definite opercula which cover up the fossa Sylvii. In Tamandua 

 the lips entirely disappear, so that we find no trace of a fossa Sylvii, for the pallium 

 above the regular arc formed by the rhinal fissure is smooth. The sulcus /3, which 

 we have seen to correspond to the supraorbital sulcus of the Dog, is represented Ijy 



Fiff. 25. 



bulb, olfact. 



lob. ant. 

 fis9. prima 



lob. flooculi 



medulla oblong 



area A 

 i'" area B 



area 



Dorsal surface of braiu of Tamandua ietradacti/la. Nat. size. 



a short oblique sulcus which does not apj^roach nearer than 4 mm. to the rhinal 

 fisssure in our type-specimen. This sulcus is constant in the six hemispheres which 

 I have examined, as well as in the figures of Pouchet and Forbes. It is even visible as a 

 depression upon the cranial cast which Gervais represents. This is the most constant 

 sulcus upon the cranial surface of the pallium in Tamandua. In this connection it is 

 not withovit interest to note that, according to Krueg f, it is one of the earliest fissures 

 to make its appearance in the development of the pallium in the Cat, as well as in the 

 Sheep and Ox. 



* W. A. Forbes, q/). cit. fig. 5. 



t Julius Krueg, Zeitsch. f. 'wissensch. Zool. Bd. xxxiii. 



