BY N. DE MIKLOUHO-MACLAY 579 



complete " Debouchement of the Central Sulcus into the Fissure 

 of Sylvius, " such as is described by Turner, has not yet come 

 under my "observation" (I). 



Having examined a considerable number of brains myself, I 

 have never observed it before 1881. It was in a brain of an 

 Australian Aboriginal who.died in the Sydney Infirmary. 



The Sulcus Rolando was connected with the Fissura Sylvii only 

 in the right hemisphere ; in the left, it terminated very near the 

 edge of the horizontal ramus of the Fissura Sylvii. With the 

 exception of the complete debouchement of the Sulcus Rolando 

 into the Fissura Sylvii, the position and the course of the former 

 presented in this brain nothing abnormal. (Fig. 2, A.-B.), gives 

 the illustrations of the case (2). 



Since my return from Europe, I was fortunate enough to obtain 

 two other brains of Australian Aboriginals. 



It was again on the right hemisphere of one of these brains, that 

 the variation presented itself. (Fig. 1 A). A little lower than the 

 middle, the Sulcus Rolando divides into two rami ; one, running 

 obliquely down, taking the usual course of the Sulcus Rolando ; 

 the other, the posterior, joining the Sulcus interparietal, runs 

 likewise down to the Fissura Sylvii. [This second or posterior 

 ramus can be regarded just as well as an abnormal extension of the 

 Sulcus interparietalis, as the closer examination of the correspond- 

 ing Sulci of the left hemisphere (fig. 1 B) makes it easy to 

 understand.] On the left hemisphere of the same brain, there is a 

 junction between the Sulcus Rolando and the Sulcus prsecentralis. 



The two cases of the complete Debouchement of the Sulcus 

 Rolando into the Fissura Sylvii, are also remarkable, because, out 

 of four brains of Australian Aboriginals which I have had the 

 opportunity of examining, two showed this peculiarity. 



(1). Loc. cit. p. 11. 



(2). The specimen which served as the original to these illustrations, is, I 

 am sorry to say, one of the five brains of my collection which were burned, 

 in the Linnean Societys Rooms during the fire of the Exhibition building 

 in 1882. 



