294 MR. W. A. FORBES ON THE GREAT ANTEATER. [Mar. 7, 
above by a shallow fissure (a), which, at the level of the anterior 
extremity of the prominent “hippocampal lobe,” turns downwards, and 
runs along the external and inferior face of that lobe till it terminates 
on its inner face (fig. 4, a), not, however, reaching the hippocampal 
sulcus (2). At the point where its downward course commences 
there is a small triangular area (/. s.s.) exposed on the lateral surface 
of the brain, from which a short curved shallow sulcus (s) runs a 
short way upwards, forming with the descending part of a a forwardly- 
convex curve. In the larger specimen figured (fig. 3) this short 
upwardly-running sulcus (s) is separated, as will be seen, by a narrow 
bridging fold from the triangular depression and its posterior continu- 
ation (a). From the antero-inferior angle of this triangular space, 
but separated by a very narrow, more or less deep, bridging convolu- 
tion from a, another sinuous fissure (0) runs forwards and upwards 
to terminate near the anterior angle of the hemisphere’. Above, 
on the supero-lateral aspect of the brain, and nearly parallel with 
the median longitudinal fissure, is a distinct longitudinal sulcus (c), 
convex upwards, which runs in an antero-posterior direction for a 
space of 1-2 inch. 
Finally, parallel with the posterior edge of the hemisphere, dividing 
the external surface of this ‘‘ temporal lobe,’’ is a vertically-directed 
sulcus (@) about °75 inch in extent. 
On the internal aspect of the brain (fig. 4) runs a well-marked 
“ calloso-marginal” sulcus (¢.m), broken up into three or more 
parts, the most posterior being nearly vertical in position, and sepa- 
rated by but a little space from the posterior extremity of fissure a. 
In its usual position is a well-marked hippocampal sulcus (4), with 
a broad “ fuscia dentata’’ between it and the corpus fimbriatum, 
the fuscia dentata being continued, as described by Prof. Turner in 
Dasypus*, as a thin layer of longitudinally-disposed fibres over the 
corpus callosum to near its genw. The hippocampal sulcus does not 
extend as high as the corpus callosum. The lateral ventricle is fair- 
sized : I can see not a trace of any posterior cornu. The hippocampus 
major is strongly convex. The ‘hippocampal lobe” has, on its 
inferior aspect, a few irregular dentations developed near its antero- 
internal angle. 
In the smaller and simpler brain of Tamandua (represented dia- 
grammatically in fig. 5, p. 295), the only sulci present are those 
corresponding to a, 6, c in the larger species, with some slight repre- 
sentatives of d. 
Adopting the late Prof. Broca’s ideas * as to the nature and com- 
position of the ‘ scissure limbique,” the inferior are of this is clearly 
represented by the fissure a, which is separated by a narrow “ pli de 
passage rétro-limbique” (fig. 4, 7./) from its superior are, represented 
? In the smaller specimen (fig. 2), this fissure is, on the right-hand side only, 
broken up into two by a narrow bridging convolution (+). 
2 Journ. Anat. Phys. i. p. 314 (1867). 
3 «* Anatomie comparée des circonvolutions cérébrales. Le grand lobe lim- 
bique et la scissure limbique dans la série des Mammiféres,” Revue d’Anthro- 
pologie, vii. pp. 885-498, 
