256 THE BRAIN OF THE TIGER SALAMANDER 



of Broca) and some dorsally of them (stria terminalis, stria semi- 

 circularis, or stria cornea). Here the enormous enlargement of the 

 basal forebrain bundles, particularly the internal capsule system of 

 fibers, displaces the dorsal stria so that its course between medial and 

 lateral ends is a wide arc, in some species almost a complete circle. 

 At both of these terminal areas the stria makes complicated con- 

 nections with the preoptic nucleus and hypothalamus, some of which 

 were termed by Cajal the "olfactory projection tract." In Amblys- 

 toma, with smaller basal forebrain bundles, these fibers take more 

 direct courses, and they are more dispersed so that there is no com- 

 pact stria terminalis as in mammals. For description and illustrations 

 of these tracts the reader is referred to my paper of 1927 (p. 302). 

 The following connections have been described: 



1. The com. amygdalarum, crossing in the anterior commissure 



(fig. 97). ' 



2. The stria terminalis sensu strido (fig. 96), a massive connection 

 passing downward from the amygdala medially of the basal forebrain 

 bundles. Some of its fibers are directed rostrad toward the septal 

 area, but most of them turn posteriorly in the dorsal fascicles of the 

 medial forebrain bundle to reach the preoptic nucleus and dorsal part 

 of the hypothalamus. The rostrally directed fibers of this group and 

 the commissural fibers are comparable with the fascicles of the stria 

 which in mammals follow the taenia semicircularis and tail of the 

 caudate nucleus, arching over the internal capsule and connecting 

 the amygdala with the septal field. None of the fibers of this tract are 

 drawn in the figures of horizontal sections. At the levels of figures 

 27-30 the descending fibers accompany the tr. olfacto-habenularis 

 medialis and then turn spinalward in the dorsal fascicles of the medial 

 forebrain bundle. Accompanying these are shorter myelinated fibers 

 which pass between the amygdala and the nucleus of the olfacto- 

 habenular tract— the tr. amygdalo-thalamicus (p.- 248). 



3. The ventral olfactory projection tract, descending from the 

 amygdala externally of the basal forebrain bundles. These fibers are 

 shown but not named in figure 16 of 1927. 



4. The dorsal olfactory projection tract (p. 242, figs. 19, 25, 26, 27, 

 ol.p.tr.) . 



STRIA MEDULLARIS TIIALAMI 



In cyclostomes, with incomplete evagination of the cerebral hemi- 

 sphere, the connections between the dorsal parts of the telencephalon 



