1895.] BEAIX IN THE LEMUES. 143 



Nycticebus has been described and figured by Sir William Flower ^ 

 and compared with Lemur nigrifrons. Burmeister '^ has dealt with 

 the brain of Tamiiis and given a figure thereof. Van der Hoeven 

 and van Camper ^ have described but not figured the brain of the 

 Potto. Owen has given ' an illustrated account of the brain of 

 Chiromys. Finally Milne-Ed«"ards ■" has published figures and 

 descriptions of the brain in Avahis laniger and other Indrisinae ; 

 and Gervais ^ 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 anjuaneiisis 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 and 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 rujlpes 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 lai'ger brain. 



' " On the Brain of the Javan Loris," Tr. Z. S. vol. v. p. 103. 



- ' Beitrage zur naheren Kenntniss der Grattung Tarsius,' 1846. 



^ 'Ontleedkundig Onderzoek van den Potto van Bosnian.' 



* " On the Aye-aye," Tr. Z. S. vol. v. p. 68. See also Oudemans, Nat. Verb. 

 Akad. Amsterdam, xxvii. 



^ Hist. Nat. de Madagascar, Mamm. p. 193. 



^ " Memoire sur les formes cerebrales propres a I'ordre des Lemures," J. Zool. 

 i. p. 1. 



