148 ON THE BEAIN IN THE LEMUKS [Feb. 19, 



family by itself. Its most marked characters are (1) the pro- 

 duction of a large semicircular sulcus by the fusion of tiie Sylvian 

 with the parieto-oceipital fissures ' : (2) the length of the angular 

 sulcus which blends in front with the iufero-frontal and gives off 

 two branches, one running downwards parallel with the Sylvian 

 fissure, the other running inwards towards the middle line^. 

 The former character is the most distinctive ; for the long angular 

 sulcus fused with the infero-frontal is met with in the Lemurince, 

 and there are in them and in other Lemurs traces of the two 

 branches in the presylvian fissure, and in the indentation to which 

 I have referred as lying in the widest part of the sagittal gyrus. 

 As to Tarsius, it has so smooth a brain that no inferences can be 

 drawn. 



There remains the family Lemuridse, of which four subfamilies 

 are commonly allowed, viz., Lemur ince, Indrisince, Gctlaginince, and 

 Lorisince. 



The first mentioned subfamily has a very uniform type of brain- 

 structure. The differences between Hcqjcilemur and Lemur, which 

 I indicated some years since, are removed by the examination of a 

 larger series of brains of Lemur. Indeed the only difference 

 which I thought myself justified in pointing out was the contin- 

 uity in Hapcdemur of the angidar and infero-frontal fissures ; but, 

 as I have mentioned in the present paper, the continuity is more 

 marked in Lemur mongoz. 



The Lorisince, on the other hand, do not form so natural an 

 assemblage as do the Lemurince. It seems as if we had in this 

 group the few remnants of a formerly much larger series — a 

 suggestion which is borne out by their wide and scattered distri- 

 bution. They all, however, agree to differ from the Lemurince in 

 the shortness or even rudimentary character of the angular and 

 infero-frontal fissures, which do not nearly meet, and in the 

 presence of the parieto-oceipital fissure near the middle line of 

 the brain. These remarks, of course, hardly apply to the small 

 and smooth brain of Loris. 



The Galaginince have as their most distinctive character the 

 absence or feeble development of the antero-temporal fissure. 

 They seem to be most like the Lorisince in other characters. 

 They resemble them in the shortness of the angular fissure, and 

 Oalago has a further point of likeness to Perodicticus and Nycti- 

 cebus in the cross-like parieto-oceipital structure. 



In all the Indrisince figured by Milne-Edwards this last mentioned 

 fissure is well marked. But as I have not examined the brains 

 of any of this group, I do not venture upon the expression of any 

 opinion as to their affinities. 



^ They are separated according to Oudemans. 



^ Or nearly ; see Oudemans, loc. cit. pi. iii. figs. 12, 14. 



