608 



MR. F. E. BEDDARD ON THE 



[Dec. 6, 



side only, and separates the temporal from the frontal lobe ; I 

 have no hesitation in terming this the Sylvian fissure. 



In the brain of Lagostomus (fig. 2, p. 599) the same fissures are 

 present, but differently developed ; a is broken into two separate 

 fissures on each side, h has almost disappeared, c is also rudimentary ; 

 between h and c is a short fissure b' which seems to be unrepresented 

 in Dasyprocta ; of the transverse furrows d is only just indicated 

 at its junction with a, while the Sylvian fissure is very deep and 

 does not nearly reach a. 



In Dolichotis (fig. 5) a is even longer and stronger than in 



Fig. 5. 



Brain of Dolichotis patagonica. 

 A, from the side ; B, from above : S, Sylvian fissure ; R, rhinal fissure. 



Dasyprocta ; b is not parallel to a, but converges towards it anteriorly ; 

 h is well developed and consists of two separated portions; c is fully 

 developed ; the only trace of c? is a bend in the furrow a at the 



