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Show 1895.] BE AIN IN THE LEMURS. 143 Nycticebiis has been described and figured by Sir William Flowerl and compared with Lemur nigrifrons. Burmeister2 has dealt with tbe brain of Tarsius and given a figure thereof. Van der Hoeven and van Campers have described but not figured the brain of the Potto. Owen has given4 an illustrated account of the brain of Chiromys. Finally Milne-Edwards5 has published figures and descriptions of the brain in Avahis laniger and other Indrisina?; and Gervais6 has written a more comprehensive paper than any of these, but his drawings are all from intra-cranial casts. § The Brain of Lemur. Having had so many different species of Lemur for examination, I am able to say something as to the range of variation in the convolutions of this genus. This range is not large, but the bigger brains are on the whole more complex than the smaller. Lemur anjuanensis has the simplest brain of all the species I have examined. It is almost precisely like L. nigrifrons figured by Flower. In Lemur albifrons the angular aud infero-frontal sulci very nearly join ; on the lateral aspect of the brain two small sulci are visible, which are represented by the merest traces in Lemur anjuanensis; the first of these is in front of the Sylvian fissure, and runs obliquely upwards at right angles to the infero-frontal sulcus. The other fissure is a commencing division of the medio-temporal gyrus. In Lemur ruflpes the angular and infero-frontal fissures do not join; in the middle of the widest portion of what may perhaps be termed the sagittal gyrus is a deep, but very short furrow on each side. In this brain, as in those of all the species of the genus Lemur, the angular fissure has the form of an elongated S. The small perpendicular presylvian fissure has another in front of it. There are the same indications as in Lemur albifrons of a division of the medio-temporal lobe. Lemur brunneus hardly differs. On one side of the brain, however, there was a very considerable furrow half an inch long, dividing the upper part of the medio-temporal lobe. In the brain of Lemur mongoz the angular and infero-frontal sulci are completely continuous. Otherwise there are no special points to be noted. Of Lemur coronatus I have examined two brains from two individuals, which, though of different sizes, were both females. In neither were the angular and infero-frontal sulci continuous. Both presylvian fissures were present, at least in the larger braiu. 1 " O n the Brain of the Javan Loris," Tr. Z. S. vol. v. p. 103. 2 ' Beitrage zur naheren Kenntniss der Oattung Tarsius,' 1846. 3 ' Ontleedkundig Onderzoek van den Potto van Bosnian.' 4 '•' On the Aye-aye," Tr. Z. S. vol. v. p. 68. See also Oudemans, Nat. Verh. Akad. Amsterdam, xxvii. 5 Hist. Nat. de Madagascar, M a m m . p. 193. 6 " Memoire sur les formes cerebrales propres a l'ordre des Lemures," J. Zool. i. p. 1. |