1882.] 



MR. W. A. FORBES ON THE GREAT ANTEATER. 



295 



by what we commonly call the "calloso-marginal sulcus" (c.w, &c ). 

 The slight sulcus at s, developed above the triangular depression, 

 will accordingly be tlie Sylvian fissure, b is then, following Broca's 

 identifications, the fissure of" Itolaudo, the gyrus lying anterior to 

 and below it being the reduced equivalent of the frontal lobe. As 

 has already been pointed out, this gyrus is connected posteriorly by 

 a small, sometimes deep, bridging fold with the triangular space (/• 

 s.s.) below the Sylvian fissure. This triangular space is I3roca's 

 " lobule sous-sylvien," its ecpiivaleut in the Primates being the lobe 

 of the island of Reil (I. c. p. 430). 



The longitudinal sulcus c corresponds probabl}' to Broca's " sillon 

 parietal primaire ; " the gyrus above and internal to it will thus be 

 the " circonvolution sagittule," that below it the " civ convolution 

 sylvien," which in the more-convoluted of the brains figured (fig. 3) 

 becomes divided up by smaller sulci (rf, e, &c.) into a number of 

 imperfect gyri. 



Fig. 5. 



Diagram of right cei-ebral hemisphere of Tamandua tetradactyla, from above. 



From my study of the brains of the remaining genera of Edentata, 

 I have httle doubt that the sulci a, b, and c, here described, can be 

 traced, with various modifications, in nearly all the members of this 

 group. Oryctei-opus in its cerebral characters seems to approach 

 Myrmecophaya more nearly than any other form, the sulci and gyri 

 of the brains of the two forms, as well as their general conformation, 

 being very similar ; Munis seems to possess the three typical sulci 

 well developed ; and these are also present in the larger Dasypodidae, 

 though apparently much reduced in the smaller forms of that group. 

 The Sloths conform to the same general type. But, in the absence 

 of a larger series of brains of this group than is at present available 

 for comparison, satisfactory generalization on this subject is impossible, 

 most of the published figures of Edentate brains being very unsatis- 

 factory in detail, whilst nothing of importance is known as regards 

 the development of the sulci in any member of this group. 



