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Show 1S99.] DR. A. KEITH ON THE CHIMPANZEES. 297 Mr. Mackay. Avhom I believe to be reliable, adding so considerably to our knowledge of the habits of the Chimpanzee that I Avish to give them here. She is, so far as I know, the first Chimpanzee that has ever lived long enough in captivity to complete its permanent dentition. All her permanent teeth have cut, with the doubtful exception of the third molar on one side, and it becomes important to determine her age so as to ascertain the period of life at which these animals attain a complete set of permanent teeth. Man attains his about the twenty-second year, but the Chimpanzee evidently much earlier. Johanna has been twelve years in captivity-six years in Messrs. Barnuin and Bailey's Menagerie, six years in the Zoological Gardens at Lisbon ; and we may infer, as it is the common age, that she was oue or two years old when Portuguese traders brought her there from the West Coast of Africa, probably Loango. When she came into his care six years ago, Mr. Mackay is positive she had then cut all her permanent incisors. From the appearance of the third molars, I think the permanent dentition has been completed very recently, so that we may accept the 12th or 13th year as the terminal period of the Chimpanzee dentition. As is usual in the female Chimpanzee, the canine teeth cut before the last molars. There are onlv two other records of the period at which the Chimpanzee teeth erupt. One is the case of " Sally " \ She was probably teu years of age when she died ; the permanent premolars had cut, but the canines and the second and third molars had not appeared. Ehlers 2 also records the case of a Chimpanzee in which the permanent dentition was being completed about the 11th or 12th year by the eruption of the canine and last molar when the animal died. 2. Menstruation. Little is known concerning the menstruation of the Anthropoids. The only observation is that of Ehlers~. of a Chimpanzee which began to menstruate about the tenth year, and continued, until it died two years later, to show a monthly discharge. Mr. Mackay's observation on '-Johanna" verifies Ehler's statement ; she began to show a monthlv discharge when she was believed to be ten years old. The discharge appears every 28th dav, and lasts for three days. It is sanguineous in colour, profuse, amounting to perhaps 4 or 6 oz., staining freely ber skirt. She is then very irritable. For 6 to S days before the discharge appears she is in heat, the genital labia are turgid and swollen; the nipples are fuller and more erect. When the discharge appears, the state of turgescence in the pudendal organs passes awav. She shows a friendly disposition to men rather than to women. She frequently plays with her nipples, but has 1 BEDDARD. F. " Contributions to the Anatomy of the Anthropoid Apes," Trans. Zool. Soc. Lond. 1892. vol. xiii. pp. 177-218. 2 EHLERS, P. " Beitrage zur Kenntniss des Gorilla und Chimpanse," Abh. pbys. CI. Gfs. Wiss. Gottingen, 1881, Bd. xrriii. No. 1, 77 pp., i pis. |