444 C. JUDSON HERRICK 



zona limitans lateralis. These fibers have been variously inter- 

 preted by different authors. I have Golgi impregnations which 

 show without ambiguity the whole course of this tract. Its 

 fibers reach the so-called corpus striatum where they break up 

 into a dense neuropil among the dendrites of the "striatum" cells. 

 Fibers emerge from this neuropil and decussate in a separate 

 (unmedullated) slip of the anterior commissure which connects 

 the "striata." Others connect with the rostral end of the hypo- 

 thalamus, where they decussate wholly or partially in the post- 

 optic commissure system. The latter are probably both ascend- 

 ing and descending fibers, and the ascending fibers correspond 

 to the tractus pallii of selachians, as has been pointed out to me by 

 Professor Johnston. There are very numerous unmedullated 

 fibers which leave the neuropil in the "striatum" to arborize 

 freely in the adjacent lateral wall of the hemisphere and posterior 

 pole. These come chiefly from the hypothalamic tract. Med- 

 ullated fibers leave the nucleus for the pars ventralis thalami, 

 some of which decussate in the anterior commissure. These 

 form part of the tractus strio-thalamicus. Finally, there is the 

 medulla ted and unmedullated connection with the stria medullaris 

 which I interpret as tractus habenulo-striaticus (see p. 429). 

 These relations are shown diagrammatically in fig. 41. 



There is no differentiated corpus striatum in the Amphibia 

 in the sense in which this term is used in mammals. The elements 

 from which it is to be differentiated are present in the pars ventro- 

 lateralis. 



The lateral forebrain tract is related to this part as in urodeles, 

 its ascending fibers including strong tracts from the colliculus in- 

 ferior and from the pars dorsalis thalami and corpus geniculatum 

 laterale. These fibers terminate in both the ventral and dorsal 

 lateral parts of the hemisphere and partially decussate in the an- 

 terior commissure. 



The pars dorso-lateralis (formatio pallialis lateralis, Gaupp) 

 lies between the fissura endo-rhinalis and the dorsal angle of the 

 hemisphere. It extends from the olfactory bulb to the posterior 

 pole, of which it forms the lateral wall. Tt receives a strong tract 

 from the olfactory bulb and is broadly connected by very com- 



