THE BRAIN IN THE EDENTATA. 



311 



further forward than the lower, is rounded and is placed upon the dorsal side of the broad 

 anterior end of the fimbria. 



ventr. olfact, 



fiss. rhinal. 



: ped. olfact. 

 bulb, olfact. 



lob. pyriform. 



.' ; tract, opt. ; liiPPOcamP- 

 Corp. paracommisB. • fimbria 



commiss. ant. 



Left hemisphere of Orycteropus ; the lateral wall removed and the lateral ventricle opened. Nat. size. 

 x. " Complete " invagination of the ventral wall of the olfactory bulb. 



If we make a horizontal section through this hippocampal swelling at about the middle 

 of its extent, we gain a more exact idea of the extent of the prominence and the 

 relationship between those parts of the hippocampal formation which make their 



fascia dentata 



inversus . fascia ; 

 dentata: 



fimbria 



fiss. hippocampi 



pallium 



Semi-schematic representation of a transverse section through the hippocampal formation in Ori/ctcropus. 



Enlarged 4 diam. 



X. Hippocampo-pallial junction, i/. Corona radiata. 



appearance upon the surface and the deeper-lying parts which produce the large 



ventricular bulging. 



In such a section the hippocampal formation presents, roughly speaking, an elliptical 



43* 



