302 ON THE ANATOMY OF 



front of the cerebral hemispheres : in the lateral view of the brain they 

 occupy, at least anteriorly, almost the lower half of the parts there ex- 

 posed. They are continuous basally with the well-developed " hippo- 

 campal lobe," in front of which appears a large oval swelling of grey 

 matter, on the middle root of the olfactory lobe, of an antero-posterior 

 extent of more than half an inch. Towards their base, the olfactory 

 tracts are curiously marked by slight transverse impressions (fig. 3) 

 giving them a striated appearance, which may also be observed in the cor- 

 responding regions in the brains of Tamandua and Orycteropus. The 

 cerebral hemispheres are but little arched superiorly * ; but the vermis 

 cerebelli is very prominent, rising above the general level of the hemi- 

 spheres (fig. 2). Viewed from above, the hemispheres appear somewhat 

 truncated posteriorly, though they here completely conceal the corpora 

 quadrigemina, abutting on the cerebellum (fig. 2). Attaining their 

 greatest breadth anterior to this, a little in front of the level of the pos- 

 terior end of the median fissure (1-95 inch long), they taper somewhat 

 rapidly anteriorly. 



The cerebellum is well convoluted, with its lateral extent (1-5 inch) 

 greater than its antero-posterior (1-15). The vermis is much narrower 

 than the lateral lobes ; it is prominent, and in one specimen (the larger) 

 considerably twisted on itself. The flocculi are distinct. 



The nates are much larger than the testes : the latter are very narrow 

 from before backwards as compared with their combined transverse 

 extent (-075 : '6 inch), and are not distinctly separated from each other. 

 The nates are larger, more prominent, and distinctly paired, being sepa- 

 rated by a well-marked constriction ; they are somewhat triangular in 

 shape, with their longer axis transverse. 



P. Z. S. 1882, The pineal gland has a distinct hard mineral deposit ; its peduncles are 

 easily made out. 



There is no very distinct corpus mamillare, it being only represented 

 by a white swelling on the infundibulum. The hypophysis cerebri is very 

 large. The anterior commissure is distinct, but not particularly large, 

 its antero-posterior extent being '15 inch. The soft commissure is very 

 large ('25 inch long) ; the posterior distinct. The third nerves are 

 small, the optic not large. 



There is a good septum lucidum ('25 inch deep anteriorly), with a con- 

 tained fifth ventricle. The fornix is very well developed, with but few 

 precommissural fibres. The corpus callosum is very well developed, more 

 than an inch long, and nearly horizontal in position, with but a slight 

 genu anteriorly. Posteriorly it forms, with the fornix, a prominent pad 

 (bourrelei). 



* Gervais's figure, L c. fig. 3 a, makes their outline much too convex antero- 

 postcriorly. 



