Mr. W. H. Flower on the Brain of the J avail Loris. 151 



their attachment to the under surface of the anterior lobe. The 

 fissure of Sylvius divides them from the temporal lobe. The orbital 

 surface of the hemisphere, as seen on each side of the olfactory lobes, 

 is hollowed out, and presents a simple longitudinal sulcus. The 

 optic nerves are small for the size of the brain ; behind them is a 

 prominent, round, whitish mass filling up the greater part of the 

 interpeduncular space, in which the corpora albicantia are not clearly 

 distinguished from the tuber cinereum. The crura cerebri are of 

 moderate size. The pons Varolii is not much elevated ; it is distinctly 

 marked off in front, but very indefinitely separated from the medulla 

 behind. The last-named body is broad and flat anteriorly, the 

 median groove distinct, its other divisions but faintly indicated. The 

 nerves appear all to rise in the situations usual in this group of animals. 



"The corpus callosum is 0*65 inch long, and covers half of the 

 anterior pair of the corpora quadrigemina. Of these bodies the an- 

 terior are the largest, they are flat and rounded in outline ; the pos- 

 terior are small, but very prominent. The posterior part of the 

 fornix is very broad, covering the optic thalami, and forming a wide 

 lamina (corpus fimbriatum) descending into the middle corner of the 

 ventricle. The hippocampus major is of moderate size. With all 

 the care taken, it was not possible to ascertain satisfactorily the extent 

 to which the ventricular cavity passed into the posterior lobe ; but 

 this is a circumstance of very little importance, and varies greatly 

 even in the same species of Quadrumana. On the other hand, it is 

 of considerable anatomical and physiological consequence that the 

 portion of grey matter homologous to that forming the so-termed 

 ' hippocampus minor' of the human subject, only of proportions corre- 

 sponding to the greater relative depth of the calcarine sulcus, exists 

 in this brain, as in that of Lemur and Galago and all the true Apes. 



" The brain of Stenops conforms closely with that of Lemur, both 

 in its general form and the disposition of its surface-markings. The 

 principal differences that were observed between them are described 

 in the paper ; and then follows a comparison of the brains of these 

 two animals with those of the higher Quadrumana. As has been so 

 well shown by M. Gratiolet, in his beautifully illustrated memoir 

 upon this subject, a certain type both of general configuration and 

 of surface-markings pervades the brain of all the Primates, from 

 Man to the Marmoset. From this type M. Gratiolet excludes the 

 Strepsirrhine Quadrumana, placing them, with the Insectivora, in a 

 group of Mammalia whose cerebral organization he considers to be 

 quite distinct from that of the two first families of Quadrumana. 

 The author of the present paper finds reason to dissent from this 

 proposition, and upon cerebral characters alone would retain the 

 Lemurs in the position assigned to them by the majority of systematic 

 zoologists — admitting, however, that, while possessing certain very 

 important points of structure peculiar to the Primates, they are in 

 many respects, especially in the shortness of the posterior lobes, an 

 aberrant group, forming a transition towards the Cheiroptera, Car- 

 nivora, and other inferior Mammalia." 



This paper will be published at full length in the Society's 

 ' Transactions,' and appropriately illustrated. 



