600 MR. F. E. BEDDARD ON THE [I^fC- G, 



commences about 5 mm. from the posterior end of the brain 

 and at about the same distance from the interhemispheral 

 fissure ; this furrow is slightly oblique in direction, the anterior 

 end being nearer to the middle line than the posterior. In 

 front of this is another furrow, rather deeper but about tlie 

 same length ; this furrow is twice the distance from the median 

 fnrrow, that is the last described furrow, and shows a tendency (on 

 one side) to bifurcate anteriorly. If the anterior end of the pos- 

 terior furrow were bent away from the middle line of the brain, it 

 would come to be continuous with the anterior longitudinal furrow ; 

 as it is a space of 3 mm. separates the two. Parallel with the 

 posterior longitudinal furrow are two less conspicuous fissures ; they 

 run at about equal distances from each other and from the furrow 

 first described : the inner of the two is only just visible ; it is very 

 short and very plainly marked : the outer is 10 mm. in length ; it 

 starts from the posterior border of the hemisphere ; but the posterior 

 part of this fissure is much shallower than the anterior half, and 

 is indeed only plainly recognizable on the right hemisphere. The 

 Sylvian fissure is very deep on the upper surface of the brain 

 though shallow at its commencement ; its direction is on the whole 

 at right angles to the longitudinal axis of the brain ; it is, how- 

 ever, curved, the convexity of the curve being forwards ; at about 

 the middle of its course it gives off a short forwardly running 

 branch, the direction of which is also slightly downwards. 



On the under surface of the brain the only distinct fissure (apart 

 from the Sylvian) to be seen is the rhinal fissure. This is quite 

 obvious from end to end. This fissure can be traced back on 

 the posterior aspect of the hemispheres up to within 6 or 7 mm. of 

 the upper surface of the brain. 



Eystrix cristata^. — Total length Ab mm., breadth 36 mm., 

 height 20 mm. 



The cerebral hemispheres are very broad and together have an 

 almost circular contour. They diverge posteriorly so as to reveal 

 the corpora quadrigemina. The upper surface is furrowed to some 

 extent, though not to so marked a degree as in some other genera. 

 The length of each hemisphere is 30 mm. 



A longitudinal furrow about 10 mm, long runs on either side of 

 the median furrow on the posterior half of the hemisphere ; rather 

 in front of the middle of each hemisjihere, this furrow is very 

 nearly continuous with a much deeper furrow passing obliquely 

 outwards at an anji,le of about 30° with the transverse axis ; this 

 furrow, which is about 13 mm. long, is restricted to the dorsal 

 surface of the brain. The remaining furrows are decidedly asym- 

 metrical in their arrangement. 



On the left half of the brain there are two downwardly directed 

 fissures running parallel with the Sylvian fissure. On the right 



' Figuied by Leuret and Gratiolet (8, plate iii.). 



