THE MONK.[103]
BRAIN OF MONK.
(From the Proceedings of
the Zoological Society.)
This Monkey is introduced here with a view of explaining the general characteristics of the brain of the group.
The brain of one of these Monkeys weighed 460 grains, or the one-eighteenth part of an entire but emaciated body. The general form is a regular arch, and the cerebellum is covered by the brain proper. Its general form is like that of some of the Cebi, and is less pointed than that of the Old World Apes in front, and less elongated and depressed than those of the lowest Monkeys of the New World, such as the marmosets and Tamarins, for instance.
On the outer surface of the brain there are few but deeply-cut and characteristic furrows. The fissure of Sylvius slopes backwards and upwards, but not very far back, and ends abruptly. On the front lobe there is a deeply-marked fissure, running crossways, backwards, and outwards, and bent in the middle. Separated from this by a wide interval is the fissure of Rolando. The external perpendicular fissure so common in the Old World Monkeys is just visible. On the inner surface the sulci are present in a simple form, and the calcarine sulcus is well curved, and prolonged and bifurcated. This is a better organised brain than that of the Howler, and is not unlike that of the Spider Monkey.
The second series of the Sakis, or those with only a short tail, or a stump of three inches in length, are called Brachyures, from this peculiarity.
MONK. (From the Proceedings of the Zoological Society.)