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Show 16 MR. F. E. BEDDARD ON THE [Jan. 20, hemisphere of a brain of S. hypoleucus. This I have not seen in Nasalis. This same brain (of S. priamus) and a brain of S. entellus show on both sides an unusual condition of the inferior temporal fissure, which is well developed and runs parallel with the Sylvian and parallel fissures. The more usual condition in this genus is a much shorter fissure which is more transverse in direction, and that is the condition which obtains in Nasalis. The fissure is not figured at all by Kiikenthal and Ziehen, but is mentioned as being very feebly developed. Another furrow which I find to vary in the &1einnopit1tecus brains at my disposal is the calloso-marginal sulcus; it sometimes bends up and cuts the surface of the brain. In Nasalis it always does. §. The Brain of Colobus vellerosus. Broadly speaking the brain of this monkey is very like that of a Macaque. There are, however, a few small points of difference, of which one at any rate may be of some little significance. The resemblance is so close in most particulars that it is really unnecessary for me to describe the brain in detail. The drawing exhibited herewith (text-fig. 5, p. 17) will adequately prove my statement. I may, however, remark that the fissure of Rolando quite cuts the inter-hemispheral sulcus: that the postcentralis is well marked on both sides : that the precentralis superior is recognizable and has a direction parallel with the long axis of the brain. On one side (the right) the Sylvian and parallel fissures join above, as is so common on both sides with the Macaques. The occipital lobe is very smooth, as is often the case with the Macaques, and the lateral occipital sulcus is hardly marked at all. The cross-piece of the characteristically Macacine calcarine fissure is visible when the brain is inspected from above. A small fissure, which I have not observed in other Old World Monkeys, is to be seen on either side, behind the Simian fissure, and running parallel with the longitudinal axis of the brain. Kiikenthal and Ziehen figure, but give no name to an apparently similar fissure (lettered B) in the brain of Lagothrix humboldti. I am able to confirm their demonstration of fact. They do not figure the same fissure in any of the Cercopithecidae. I am unwilling to seem to emphasize too strongly this point of likeness between the African Colobus and the New World Lagothrix; but I may remind zoologists that likenesses between Colobus and the New World Monkeys have been pointed out. More important than this, however, is the light which the brain-structure of Colobus appears to throw upon its relationship to other Old World genera. On account of the structure of its stomach, and for some other reasons also, Colobus has been associated with Seinnopithecus into a subfamily Semnopithecina?, contrasted with the Cercopithecinse which embraces the remaining Cercopithecidse. It should be plain from the statements made in |
