THE GREAT ANTEATER. 303 



The cerebral sulci are not exactly alike in my two specimens, the brain 

 of the bigger of the two animals, though of the same dimensions as its P. Z. S. 1882, 

 fellow, being more richly convoluted by the development in it of minor p< 293 ' 

 fissures and impressions not present in the other. It is that of which 

 the lateral and internal views are here figured (figs. 3 & 4, p. 301) : the 

 description of the main sulci is taken from the simpler specimen 

 (represented in fig. 2), but applies in all essential respects to both. 



The olfactory lobe is separated from the cerebral hemispheres above by p. z. S. 1882, 

 a shallow fissure (a), which, at the level of the anterior extremity of the P- 294 * 

 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 (A). At the 

 point where its downward course commences there is a small triangular 

 area (l.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 f or wardly- convex curve. In the larger speci- 

 men 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 continuation (a). From the antero-inferior angle of this 

 triangular space, but separated by a very narrow, more or less deep, 

 bridging convolution from a, another sinuous fissure (6) 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 (t?) about *75 inch in extent. 



On the internal aspect of the brain (fig. 4) runs a well-marked " calloso- 

 marginal " sulcus (c.m), broken up into three or more parts, the most 

 posterior being nearly vertical in position, and separated by but a little 

 space from the posterior extremity of fissure a. In its usual position is 

 a well-marked hippocampal sulcus (7i), with a broad "fascia dentata" 

 between it and the corpus fimbriatum, the fascia dentata being continued, 

 as described by Prof. Turner in Dasypus f, as a thin layer of longi- 

 tudinally-disposed fibres over the corpus callosum to near its genu. 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 



* In the smaller specimen (fig. 2), this fissure is, on the right-hand side only, broken 

 up into two by a narrow bridging convolution (-j-). 

 t Journ. Anat. Phys. i. (1867), p. 314. 



