42't PEOr. G. ELLIOT SMITH O^ THE 



type of brain is ])eculi;u-ly specialized in the genus Chiroii/i/s and the extinct Lemuroid 

 JIcguhuhipLs. 



It is impossible, with any degree of accuracy, to place the peculiarly pithecoid form 

 of brain which GloUlennir presents. So far as its characters can be determined, it 

 resembles the type of the genus Lemur and the Gulaginae. 



The Loi'isinse again present peculiar cerebral featru'es. In many respects the brain 

 is peculiarly simple, after the same manner as tliat of tlie Galagime. In FerocUcticus, 

 and to a less extent in Ni/ctlcehas, there is a peculiar tendency toward the formation of 

 the typically Primate central sulcus. 



Tarsius is obviously related, so far as the evidence of the brain is concerned, to the 

 Galaginee. This resemblance cannot be disguised even by the peculiar distortion of 

 the brain in the former. It is in every respect distinctly Prosimian. But it also 

 exhibits tAvo interesting series of features. So far as the corpus c:illosum, the hippo- 

 campal formation, and the cerebellum are concerned, the brain of Tarsius conforms 

 to the simplest Eutherian type, such as we find in the more generalized Insectivora — 

 for example, Erliiaceus. Yet its relative microsmatism (in comparison with other 

 Lemurs), the proportion of its hemispliere which is placed on the caudal side of the 

 corpus callosum, and the presence of a definite posterior cornu of the lateral ventricle, 

 all indicate a nearer approach to the Simian condition than occurs in the brain of 

 any other Lemur. Tai-sins possesses at once the most generalized and the most 

 pithecoid brain of all the Lemuroidea. 



In this connection it is interesting to quote some remarks concerning Aintptoniorphus 

 which were made seventeen years ago by E. D. Cope: — " The brain and its hemis^jheres 

 are not at all smaller than those of the Tarsius, or of the typical lemurs of the present 

 period. This is important in view of the very small brains of the tlesh-eating and 

 luigulate Mammalia of the Eocene period as yet known. In conclusion, there is no 

 doubt but that the genus Anaptomorphns is the most Simian lemur yet discovered, and 

 probably represents the family J'rom Avhich the anthropoid monkeys and men were 

 derived" *. 



Zittel also has remarked that the Eocene Lemuroids {Adapis, Mlcrocluei'iis) of Europe 

 " combine features of the existing Lemurs and true A])es " f. 



It is not easy to draw any certain conclusions from the evidence of the brain as to the 

 relations of the Primates to other mammals. 



The larger Carnivores show a tendency toward the development of a Sylvian complex 

 like that of the Primates. There is a singular al)sence of any such tendency in the 

 Ungulata. Like the latter, how^ever, the Primates always retain a coronal sulcus, which 

 in the main is nearer the horizontal than the vertical direction. It is a peculiar fact 

 (hat the separation of the calcarine and intercalary sulci, which is so marked a feature 

 of the Primates, should occur (practically) nowhere else in the Mammalia, except in the 

 three Edentate families Myrmecophagidic, Bradypodidse, and Manida^. In the case of 



* "Tlie Lemuroidea and the Liscotivora of the Euoeiie Period of Xorth America," American Naturalist, 

 May l^s."), p. 407. 



t Quoted l.y IL 0. Forbes, 'llonkeys,' vol. i. p. 111. 



