82 t TEOF. G. ELLIOT SMITH ON THE 



specimen, so that one anatomist might have the chance of describing- and comparing the 

 two brains. Dr. Charles Hose lias from time to lime sent to Mr. W. L. H. Duckworth 

 in Cambridge a valuable series of excellently preserved brains from Borneo, which I 

 have had an opportunity of examining. Mr. Duckworth very generously placed at my 

 disposal two brains of Tursius, one of which had been fixed and preserved in situ by 

 means of i'ormalin injections, and the other had been extracted with all that care and 

 skill for which Mr. Hose is so well known among zoologists. This In-ain was preserved 

 for histological purjwses inMiiller's tiuid. Mr. Duckworth also permitted me to examine 

 many other specimens, including an excellent brain of Galago Garnetti. Captain Stanley 

 Flower has kindly placed at my disposal the fresh bodies of five Lemurs and SiNycticebus 

 which died in the Ghizch Zoological Gardens diuing the last ^qw montlis, and I have 

 thus been able to examine the brain of these animals in a jjei'fectly fresh condition. He 

 has also given me skulls of Lemur macaco and Nyciicchus tardigradus. From these I 

 liave been al)le to make cranial casts. 



Dr. Forsyth Major, whose generous help has been afforded me in many ways during 

 the course of this investigation, gave me the brain of Microcebus Smithl and lent me 

 the skulls of various Lemurs. On his suggestion, the authorities in the Geological and 

 Zoological Departments of the British Museum kindly permitted me to examine their 

 large collections of crania of recent and extinct Lemurs. I have also examined all the 

 crania of Prosimije in the collection at the Royal College of Surgeons. 



1 have thus been able to study the shape of the Ijrain and the arrangement of the 

 cerebral furrows not only in every genus and most species of recent Lemurs, but also 

 in the extinct Lemur Jullyi, Globileimir, and both an adult and a young Ilegaladapis. 

 ,Vs Dr. Forsyth Major was engaged in investigating these A'aluable extinct forms, my 

 indebtedness to him is all the greater for allowing me to examine them. 



It is commonly supposed that a mould of the cranial cavity can give little exact 

 information beyond indicating the shape of the brain. In most Apes this is to a very 

 great extent true. But in most mammals in which the pattern formed by the sulci is 

 not very complex (and also even in some, especially Carnivores, in A\liich a very rich 

 supply of sulci exists) a series of prominent ridges develop on the inner face of the 

 cranial wall so as to accurately map out the plan of the sulci. These ridges are especially 

 Avell developed in all Lemurs, excepting only the extinct form Globilemur, in which the 

 pattern becomes blurred as in most Apes. 



It is, however, absolutely necessary, if one is to accurately interpret the plan of the 

 sulci from the arrangement of these bony ridges, to carefully study the actual braius of 

 several genera and the crania in whicli they were lodged, to apjjreciate several sources of 

 fallacy, which have been so unfortunately demonstrated in Gervais's imcontrolled study of 

 casts [oj). cit. supra). If this precaution be taken, one is able to map out the plan of 

 the sulci on the outer sitrface of the hemisphere in a plaster mould with the certain 

 conviction that he is accurately interpretiug the configuration of the brain itself. 



From the specimens {Lemur, Kycllcebas, Jlicrocebus, and Tarsius) M'hich I have been 

 able to devote to histological purposes, I have been able to determine many interesting 

 features in the arrangement of the fibre-tracts, especially the optic and olfactory paths 



