ON THE BRAIN OF ATELES PANISCUS SOI 
is traced backwards, and forms a great fissure, extending, in some 
parts, for as much as # of an inch upwards and outwards, and passing 
backwards until it nearly reaches the posterior margin of the 
hemisphere, where it terminates by dividing into two short, but deep, 
branches, a superior and an inferior. Traced from before backwards, 
or from within outwards, the line of this sulcus presents a strongly 
marked, but irregular, upward convexity. 
On making successive transverse sections of this cerebrum from 
before backwards (woodcut, fig. 1. A, B, C, D), the fissure was seen, in 
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Fig. 2.—View of the inner surface of the left cerebral hemisphere of A/e/es, of the natural 
size, and beneath it a corresponding view of the human left cerebral hemisphere reduced 
to the same size. In the latter only the principal sulci are indicated. 7. calloso-marginal 
sulcus ; . occipito-parietal sulcus; 2 calcarine sulcus; 7. dentate sulcus; 7. collateral 
sulcus; 2x. continuation of the callosal gyrus (18) into the uncinate gyrus (19). 
A, B, C, &c., A’, B’, C’, &c., the lines along which the transverse sections in Fig. 1 
are taken, 
its most posterior part (A), to pass almost horizontally outwards for a 
short distance, and then to divide into an upward and a downward 
branch. In front of A it forms a curve strongly convex upwards, 
without any terminal bifurcation; in B it is much longer and less 
convex ; in C it is but slightly sinuous, and in D it is a little concave 
