SEPTUM, HIPPOCAMPUS, PALLIAL COMMISSURES 421 



of the brain of reptiles and amphibians. It has been the behef of 

 most authors that this so-called^ septum in amphibians and rep- 

 tiles is the equivalent of or is intimately associated with the sep- 

 tum pellucidum of mammals. In reality it includes both the 

 medial olfactory nucleus and the equivalent of the septum pel- 

 lucidum of mammals. Adolf Meyer ('92) and Unger ('06) distin- 

 guished the septum pellucidum as an independent structure in 

 reptiles. The terms 'nucleus septi,' ' nucleus lateralis septi, ' and so 

 forth, are confusing and require revision. The nucleus septi 

 (Unger; nucleus accumbens septi, Kappers) is said by these 

 authors to belong to the striatum and not to the septum. It is 

 divided by Herrick (fig. 43) into nucleus accumbens septi and 

 nucleus lateralis septi. The latter nucleus includes in addition a 

 great part of the equivalent of the septum pellucidum (figs. 47, 

 61, 56, 64, 66). The term 'nucleus medianus septi' is used by 

 Herrick for part of the primordium hippocampi (figs. 43, 61), and 

 also for the superficial layer of cells in the area parolfactoria (fig. 

 66) . In other words, the lateral and medial nuclei 'of the septum' 

 each contains a part of the parolfactory and a part of the pallial 

 areas. Similar inconsistencies appear in the work of other 

 authors. Generally speaking, recent authors have followed Elliot 

 Smith in regarding the septum of mammals as a derivative of 

 the paraterminal body which is basal. They have consequently 

 applied the term septum to the basal part of the medial wall in 

 reptiles and amphibians. In this way the term septum has been 

 made to include both basal olfactory and pallial areas. For this 

 reason all reference to the septum should be eliminated from the 

 names hereafter used for the several nuclei belonging to the basal 

 olfactory areas. With this in view I have adopted the term, area 

 parolfactoria, and have called the superficial layer of cells the 

 nucleus parolfactorius medialis and the deep layer which is so 

 closely related to the caudate, the nucleus parolfactorius lateralis. 

 It should be noted that this area corresponds nearly to the area 

 parolfactoria of Broca, and that the writer regards as very un- 

 fortunate the recent use of the term to designate the tuberculum 

 olfactorium or an adjacent part of the anterior perforated space 

 (lobus parolfactorius, Edniger '08, p. 260; eminenza paraolfat- 



