1882. } MR. W. A. FORBES ON THE GREAT ANTEATER. 295 
by what we commonly call the “ calloso-marginal sulcus’’ (c.m, &c.). 
The slight sulcus at s, developed above the triangular depression, 
will accordingly be the Sylvian fissure. 4 is then, following Broca’s 
identifications, the fissure of Rolando, 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 (J. 
s.s.) below the Sylvian fissure. This triangular space is Broca’s 
** lobule sous-sylvien,” its equivalent in the Primates being the lobe 
of the island of Reil (/. ¢. p. 430). 
The longitudinal sulcus ¢ corresponds probably to Broca’s “ sillon 
pariétal primaire ;”’ the gyrus above and internal to it will thus be 
the “ circonvolution sagittale,’ that below it the “ circonvolution 
sylvien,” which in the more-convoluted of the brains figured (fig. 3) 
becomes divided up by smaller sulci (d, e, &c.) into a number of 
imperfect gyri. 
Diagram of right cerebral hemisphere of Tumandua tetradactyla, from above. 
From my study of the brains of the remaining genera of Edentata, 
I have little doubt that the sulci a, 6, and c, here described, can be 
traced, with various modifications, in nearly all the members of this 
group. Orycteropus in its cerebral characters seems to approach 
Myrmecophaga 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 Dasypodide, 
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 develo pment of the sulci in any member of this group. 
