502 ON THE BRAIN OF ATELES PANISCUS 
upwards and inwards. Combining these views with those given in fig. 
2, it is easy to form an estimate of the figure of the surfaces of the 
upper and under lips of the sulcus; but what is most important about 
it is, that, so far as the posterior cornu extends, the closed end of this 
sulcus corresponds with the hippocampus minor (1), which last is, in 
truth, nothing but the arch of cerebral substance which, at once, 
forms the outer boundary of the sulcus and the inner boundary of the 
cornu. 
From its special relation to the hippocampus minor, or “calcar 
avis,” I shall call this the “calcarine” sulcus; but it extends beyond 
the calcar and the posterior cornu, both anteriorly and _ posteriorly, 
particularly in the latter direction. Nevertheless it does, in a definite 
sense, correspond with the inner wall of the posterior cornu. The 
calcarine sulcus dies away anteriorly, at the point indicated, and is in 
no way continuous with that sulcus which has a relation to the 
hippocampus major similar to that of the calcarine sulcus to the 
hippocampus minor, and which, for distinction’s sake, I will call the 
‘dentate’ sulcus, on account of its relation to the fascia dentata or 
corps godronné. This narrow and well-known sulcus lies between the 
letters #z and 7, the lower 7 being placed opposite its termination in 
the fold formed by the recurved part (crochet de I’hippocampe, 
Gratiolet) of the so-called ‘uncinate’ convolution (19). Thus the 
dentate sulcus, which corresponds with the hippocampus major, is 
separated from the calcarine sulcus, which similarly answers to the 
hippocampus minor, by the rounded process of cerebral matter, x, this 
last being, in fact, the inferior and posterior continuation of the 
callosal gyrus (circonvolution de l’ourlet of Foville, pli du corps 
calleux of Gratiolet). This continuation of the callosal gyrus into 
the uncinate gyrus is regarded as an anomalous peculiarity of the 
human brain by M. Gratiolet (4 c¢ p. 64); but, so far as I have 
examined into the matter, it is similarly continued into the uncinate 
cyrus in Apes. 
Ending at a point considerably anterior to the calcarine sulcus, 
sometimes in a bifurcated extremity, there is another deep sulcus, x, 7, 
which runs, at first, roughly parallel with 4 /, but is much longer, 
being continued along the inner and under surface of the temporal 
lobe nearly to its extremity. Although not so deep as the calcarine 
sulcus, it is continued upwards and outwards, for a considerable 
distance ; and throughout its whole course, the bottom, or roof, of the 
sulcus underlies the floors of the descending and posterior cornua. If 
a vertical section be taken through the eminentia collateralis (E, p. 
489), it will be found that the arch of cerebral substance, e c, whose 
