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Show 638 MR. W. A. FORBES ON THE UAKARI MONKEYS. [Nov. 30, besides an azygos lobe, which lies behind the heart in a transverse direction, and is triangular in shape. The left lower lobe is the largest, the right lower the next. The cricoid cartilage is deeply notched above. The vocal cords are well developed, *35 of an inch long ; the ventricles have the shape of watch-pockets, extending downwards and inwards. There are no laryngeal pouches. The epiglottis is notched above. There are about 27 tracheal rings. The kidneys are smooth and rather elongated in shape ; the suprarenal bodies are well developed and oval. The ureters open *75 inch from the neck of the bladder. The ovaries measure *45 inch, the Fallopian tubes 1 inch." The uterus is single and smooth within; it is *75 inch long. The vagina is double that length ; and the clitoris is small and flattened. As regards the osteology, already briefly described by Gervais (" Remarques osteologiques sur les genres Brachyure et Galli-triche") in Castelnau's ' Expedition dans i'Amcrique du Sud ' [Paris, 1855, Anatomie, pp. 93-99], there is not much of interest to add. The vertebral formula of my specimen of Brachyurus is C. 7, B. 13, L. 6, S. 4, C. 15 or 161. Gervais gives C. 7, D. 14, L. 6, S. 4, C. 17 for B. rubicundus; the British Museum Catalogue 7, 13, 6, 3, 18, for both B. calvus and B. melanocephalus. In the latter skeleton {f'Ouakaria spixii," 806 b) I counted, however, nineteen or twenty caudal vertebrae, the first five of which bear transverse processes, whilst the terminal ones are very minute and styliform. The carpus has an os centrale, and the humerus a well-marked supracondylar foramen. The clavicles are well-developed, and strongly curved sigmoidally. The manubrium sterni is broad. I may, however, take this opportunity of pointing out a useful means of discriminating, in most cases, between the skulls of the Platyrrhine and Catarrhine Monkeys, in addition to the well-known differences in their dentition and in the form of their external auditory meatus. In nearly every skull of a New-world Monkey, it will be found that the parietal and malar bones are in contact with each other, for a more or less considerable extent, on the side walls of the skull (vide fig. 5). In the Old-world Monkeys, on the contrary, this contact never (with the exception named below) takes place, the frontal and alisphenoid bones articulating with each other, and so cutting off the connexion between the parietals and malars (vide fig. 6). In the skulls of the genus Hylobates that I have examined this isthmus is very narrow, so that the parietals and malars approach much nearer each other than is usually the case in the Catarrhnn; indeed, in one specimen in the College of Surgeons Museum ( 5 0 2 7 B ) the malar and parietal of one side only touch each 1 In my specimen the few minute terminal caudal vertebra; have unfortunately been laid aside and cannot now be found. There were not, however, more than three or four of them, which, added to the twelve that remain, give the |