THE BRAIN OF THE LEMURS. 87 



There is a typical long intercalary furrow (si.) and the cha- 

 racteristic triradiate calcarine group. The calcarine sulcus (sc.) 

 is confluent with the retrocalcariiie {s.r.c). The paracalcarine 

 sulcus (s.pc.) is separated from the calcarine by a deeply sub- 

 merged narrow gyrus (fig. C). 



The mesencephalic depression on the hemisphere is more 

 extensive than it is in the adult Lemur, so that the calcarine 

 sulcus is placed within it as far back as its apparent bifurcatioa. 



The furrows b and c, already noted in the brain of Lemur 

 (Mem. fig. 5), are present here also. 



There is a small hippocampal tubercle. There is no posterior 

 cornu of the lateral ventricle. 



The cerebelluaa so closely resembles that of Lemur that no 

 special account is demanded. 



The extraordinary variability of the disposition of the sulci in 

 Projnthecus is such as could have been produced only by retro- 

 gressive changes from a type more richly supplied with, cerebral 

 furrows. 



The Brain o/" Lemur macaco. 



I trust to have abundantly shown in the body of the afore- 

 named memoir that the great desideratum in the study of an 

 organ which exhibits great variability is a large number of 

 accurate records. JSTo apology is needed, therefore, for adding 

 notes, even in reference to the genus Lemur. 



I have recently received from Captain Stanley Flower the 

 body of an adult female Lemur macaco, from which 1 obtained a 

 fresh brain. 



The cerebellum is exposed to the same extent as that de- 

 lineated iu tig. 3 of my memoir. The cerebral hemisphere is 

 46 mm. long, and the two hemispheres together 37 mm. broad. 



The rhiual fissure presents the usual form (cf. Mem. fig. 7), 

 only the angle being definitely developed. 



The orbital and diagonal sulci are present and well-developed, 

 and occupy the positions characteristic of the genus Lemur 

 (Mem. fig. 6), i. e. the diagonal does not cross the orbital 

 margin. 



There is an extensive, simple, linear coronal sulcus on the 

 right hemisphere ; on the left side its caudal end is bifid ; a 

 simple, obliquely-placed, comma-shaped sulcus f in the usual 

 position (Mem. fig. 1); the extensive lateral sulci are sym- 

 metrical, and both resemble that shown on the left hemisphere 



