640 MR. W. A. FORBES ON THE UAKARI MONKEYS. [NoV. 30, 



and not at all in the remaining three. In the same collection, a 

 single skull of an Ateles (4 717«) also shows no trace of this union. 



In all the remaining genera, so far as I have yet seen, the rule 

 holds good. I was first struck with the arrangement here described 

 when examining the collection of Monkeys' skulls in the Cambridge 

 jNIuseum ; and finding that there was no exception whatever, either 

 there or in the skulls belonging to the Prosector's department, I 

 examined the entire collection of unmounted skulls in the 

 College-of-Surgeons Museum (including nearly every known genus 

 of Monkey), with the results already mentioned. The character is at 

 all events worth knowing for practical purposes, even if of no greater 

 scientific value. This, of course, must be left open for more 

 extensive examination'. 



The brain of Brachyuriis rubicundus is represented in the accom- 

 panying figures (figs. 7-10, pp. C42, 643), which give views of its 

 superior,inferior, external, and internal aspects, of the natural size, 

 drawn after the organ had been hardened in spirit for a short time. 



The total length of the hemispheres is 2'3 inches, their greatest 

 breadth 1'8 inch, whilst the vertical depth is about 1'2.t inch. 

 Viewed from above, the hemispheres have a fairly rounded contour, 

 and the cerebellum does not project beyond their posterior margin, 

 though it appears above in the middle line between the somewhat 

 cut-away inner margins of the occipital lobe. From the side, the 

 hemispheres are seen to be but slightly arched. The occipital lobe 

 is well developed, and the orbital surfaces but little excavated. The 

 temporal lobes are also well developed. 



The hemispheres possess the most important sulci characterizing 

 the Simian brain well developed : as regards their comj)lexity, they 

 stand between Ateles, Gehus, and Lar/othrix, on the one side, and 

 CaJlithri.v, Mycetes, Pithecia, &c., on the other. 



The Sylvian fissure" (s.) is well developed, running upwards and 

 backwards to end, '3 inch from the middle line of the hemispheres, 

 a little in advance of the spot where the temporo-occipital sulcus 



' P.S. Jan. 27, 1881. — Mr views have beeu both confirmed and anticipated 

 by Dr. Gustav Josepl). in a paper in tlie first volume of the ' Morphologisclies 

 Jahrbueli' (i. pp. 4.">.3-(i.">, Taf. xv.). Whilst mv paper was going through the 

 press. Pro!. Flower was kind enough (o call my attention to tliis paper, as 

 well as to another by the same author in the ' Berielit der Schlesischen Gesell- 

 schaft ' — which, as yet, I have not been able to see — botii being referred to in a 

 recently published ethnological paper (in Eussian) by Demetrius Arnoutcliine, 

 which also, apparently, contains some more information on the same subject. 



- In the following description of the sulci, &c., I have in tlie main followed 

 the nomenclature proposed by Prof. Huxley in his valuable paper on the brain 

 of Ateles paniscus (P. Z. S. 18(U, pp. 247--l(>0, pi. xxix.). and adopted by Prof. 

 Flower in his descrijjtions of the bi'ains of Myccte?. scniculus (P. Z. S. 1864, 

 pp. 3.35-3.38, pi. xxix.) and FitJiccia monachus (P. Z. S. 1862, pp. 328-331). The 

 late Dr. Paul Broea has more recently written an elaborate article on the sub- 

 ject of cerebral nomenclature ("Nomenclature Cerebrale, denomination des 

 divisions et subdivisions des hemispheres et des anfractuosites de leur surface," 

 Revue d' Anthropologic, (2) i. 1878, jjp. 193-236). In this he endeavours to 

 limit more strictly than has hitherto been done the terms used by various 

 writers on the structm-e of the brain, and to introduce a uniform nomenclature. 

 I have, wliere necessary, added his names in brackets after those here used. 



