^Oi PROF. G. ELLIOT SMITH OX THE 



Tlie latter writer regards the furrow g to l)e the upper part of tlic Sylvian fissure, whicli 

 is separated from the lower part (/) by " eine kleiiie Untcrbrechung, die jedoch uur auf 

 llcehnung des Schadelaugusses zu setzeu ist " (Anat. Auz. 1002, p. 231). Natural 

 though sucli a suggestion is at a casual glance, its adoption would logically lead to many 

 difficulties in the interpretation of other furrows. Thus it is quite inconceivable that the 

 lateral (intraparietal or " interparietal " of German writers) sulcus, which we have learnt 

 to regard as one of the most stable sulci, not only in the Lemurs but also in the other 

 Mammalia, can be represented merely by the furrows d and n. The former of these {d) is 

 not even present on the right hemisphere, and ;/ is so shallow as to be of questionable 

 ^aluc. Moreover, if n is ]mrt of any furrow, it is that marked g, and not d, to which it 

 nnist be linked. If Burckhardt had suggested that the lateral (intraparietal) and the 

 suprasylviaii (Sylvian) sulci had fused as in Nycticehns, Chrysothrix, and Nyctijjithecus, 

 ihere would have been less reason for criticising his suggestion on this jiarticular point. 

 But there are other reasons which forbid us accei:)ting the suggested homology as the true 

 interpretatioa. It is hardly i^robable * that a hemisphere whicli has extended backward 

 over the cerebellum to an extent at least as great as ever occurs in Lemur should possess 

 u Sylvian fissure which slopes backward so much more slightly and occupies such a 

 forward position. And if g is the Sylvian fissiu-e and h the superior temporal, as 

 Burckhardt suggests, it necessarily follows that half of the cerebral hemisphere lies on 

 the caudal side of the latter sulcus! This would be a state of affairs for which no 

 ])arallcl exists elsewhere in the Primates. 



I do not think that Burckhardt's suggestions are at ail conckisive or even probable. 

 But, on the other hand, I cannot offer any alternative scheme w^hich is not open to adverse 

 criticism. If the furrow / had not been present f I should have confidently believed 

 that this brain retained the true Lemurid pattern of sulci, g + n being the lateral, 

 h the Sylvian, and / + ,/ being the postsylviau ; but now" I cannot do more than 

 subscribe to the opinion of Forsyth Major that "it is never safe to attempt to make out 

 the exact homologies of the fissures in a cast of the brain-cavity" [op. cit. p. 17). 



The BiiAiN ix Megaladapis. 



One can speak with much more confidence concerning the features of the brain in 

 3Iegaladapis madugascariensis, Maj. ; but most that deserves saying concerniug this 

 brain has already been admirably said by Dr. Forsyth Major %. 



The great contrast which the shape of this biain presents to that of Glohilenmr and 

 the extraordinary conformation of its anterior paits (more especially the elongation of 

 the olfactory peduncles and the relatively forward position of the optic chiasma) 

 have been clearly shown in the figures and descriptions of the work just quoted. The 



*" In making this statoment I have not forgotten fliat the Sylvian fissure may occupy such an unusual position, 

 .i'«, for instance, in Tarsius. 



t In the skull of a specimen of jS'i/clicehiis 1 have seen a bony ridge in a corresponding situation, which did not 

 represent any furrow on the brain itself. 



* Proc. Ptoy. Soc. ISiJT, pp. 47-50. 



