240 PHYSIOLOGICAL SERIES. 



On the mesial surface of the right hemisphere, note tin- 

 olfactory peduncle passing into continuity with the pre- 

 eominissural area, the upper part of which fills up the gap 

 l>rt ween the corpus callosum and the psalteriom, and is 

 commonly known as a folium of the septum luciduin. 



Underneath the splenium of the corpus callosum tho 

 subsplenial hippooampal flexure is visible, the pyriform 

 upper part being formed by the fascia dentata rapid lv 

 dwindling away as it surrounds the splenium : below the 

 tapering fascia dentata there is a little tubercle of exposed 

 hippocampus the hippocampus nudus (the so-called 

 "Balkenwindung"). 



Behind the lower half of the typical hippooampal forma- 

 tion the caudal part of the rhinal fissure is seen. It ends 

 in a bifid manner. 



The calcarine sulcus begins above the latter, ascends 

 vertically, and is then prolonged forward and with a slight 

 obliquity upward, so as to overlap, without joining, the 

 crucial sulcus: in other words, the calcarine is continuous 

 with the intercalary sulcus. It is a feature of contra -i 

 between the jiEluroidea and the Cynoidea that in tin- former 

 the crucial sulcus and the intercalary (so-called "splenial ") 

 sulcus are usually separate, whereas they commonly join in 

 the latter. There is a short marginal sulcus (Owen) abov- 

 the intercalary in the region of the splenium. 



On the mesial surface of the brain, note the cavil v of 

 the third ventricle bridged by the large " soft " or middle 

 commissure: its anterior wall formed by the delicai-- 

 lamina terminalis, which proceeds from the optic chia^ma 

 to the anterior commissure and then from the latter to the 

 ventral extremity of the psalterium ; behind the latter, tin- 

 upper extremity of the lamina terminalis is seen as a little 

 gelatinous-liko nodule, the crista, to which the epithelial 

 roof of the ventricle is attached. (The epithelial roof has 

 been removed from the specimen.*) 



* The general relations of all the structures enumerated in this and tin- 

 following four paragraphs do not change to any great extent in the 1 jit hrris. 

 Hence the reader may consult a text-book of Human Anatomy for a fuller 

 account of them. 



