362 PHYSIOLOGICAL SERIES. 



The- anterior poles of the hemispheres are remarkably 

 blunt and flattened. In this respect they present a resem- 

 blance to those of the extinct Lemuroid Megaladapis. 



The broad flattened olfactory bulbs must be considered 

 large, even for a Prosimian brain ; and the proportions of 

 the typical olfactory tubercles and pyriform lobes are in 

 accord with this fact. The rhinal fissure is clearly defined 

 in its anterior part j but it becomes obliterated behind the 

 vallecula Sylvii, so that there is no clearly defined line of 

 demarcation between the caudal part of the pyriform lobe 

 and the neopallium (fig. 207). 



There is a relatively large corpus callosum with a plump 

 splenium and a well-formed genu, which is linked to the 

 anterior commissure by a delicate rostrum. 



The lower extremity of the hippocampal formation exhibits 

 that peculiar swelling of inverted hippocampus (fig. 209, 

 HIP.TUB.) which occurs in all the Primates, and is found 

 so well developed elsewhere, so far as I know, only in 

 Orycteropus (vide "The Brain in the Edentata/' Trans. 

 Linn. Soc. 1899), and sometimes in the Manatee. There is 

 also a peculiar notch-like offshoot from the hippocampal 

 fissure just above this " hippocampal tubercle/' such as is 

 commonly found in the brains of Lemurs (compare figs. 209 

 and 212, x). 



The condition of the "cingular" group of sulci is par- 

 ticularly interesting. At a casual glance the calcarine, 

 intercalary, and genual sulci on the separate left hemisphere 

 (fig. 209) seem to be joined to form one long "cingular" 

 sulcus as, for instance, in the Tapir's brain. But a close 

 examination reveals the fact that the calcarine sulcus is 

 separated from the intercalary-genual complex (or calloso- 

 ina i ^inal sulcus, as we may now call it), as in all other 

 Primates. But in this instance the separation is effected 

 only by a very narrow, partially submerged gyrus. The 

 condition of the calcarine sulcus thus exhibited (which 

 essentially resembles not only that found in Lemurs, but 

 also that of the Edentate Manis) affords yet another demon- 

 stration of the identity of the eiilearino sulcus ofthe Primates 

 and the vertical po-terior part of the sulcus generally called 

 "splenial" in other mammals. 



