426 C. JUDSON HERKICK 



these plexuses see beyond, p. 431). Here in the eminentia thai- 

 ami, which borders the taenia (figs. 16 to 19), many fiber systems 

 are crowded together. 



The observed relations are these, the following tracts being 

 all unmedullated except as specified. The fimbria complex, bear- 

 ing a fewmedullated fibers (fig. 15) connected with the primordium 

 hippocampi, divides into two parts, each with medulla ted fibers, 

 one entering the commissura pallii anterior, the other the stria 

 medullaris (fig. 16). Medullated fibers pass between both of 

 these subdivisions and the adjacent grey of the pars ventro- 

 lateralis hemisphaerii (striatum complex). Both subdivisions 

 have unmedullated connections with the posterior pole. Far- 

 ther back (figs. 18 and 19) the stria medullaris has an unmedul- 

 lated connection with the eminentia thalami and a strong medul- 

 lated and unmedullated connection with the rostral end of the 

 pars ventralis thalami. Golgi preparations of adult Necturus 

 show that some at least of the fibers between the stria medullaris 

 and the pars ventro-lateralis hemisphaerii, pars ventralis thalami 

 and eminentia thalami end in these parts by free arborizations. 

 In view of the fact that these are all centers of efferent discharge, 

 I interpret these fibers as conducting downward from the habenula 

 to the somatic motor correlation centers. 



There is also a strong connection between the stria medullaris 

 and the preoptic nucleus, which is very large in urodeles. This 

 tract runs chiefly external to the lateral forebrain tract but partly 

 internal to it. A few medullated fibers are found in the latter 

 path (fig. 19). This tractus olfacto-habenularis lateralis et media- 

 lis reaches as far forward as the pars ventro-medialis hemisphae- 

 rii and possibly as far back as the hypothalamus. Johnston 

 describes in Necturus a tract from the "medial olfactory nucleus" 

 (nucleus medianus septi) to the commissura pallii anterior. I 

 find the tract in Necturus and in the frog in the same relations 

 as figured by Johnston ('06, p. 306, fig. 150). Golgi preparations 

 of adult Necturus show that these fibers arise chiefly from the 

 bodies of cells bordering the recessus superior. These cells lie 

 very close to the ventricle and look like ependyma cells, though 

 probably they should not be classed as such. This tract doubt- 



