128 Journal of Comparative Neurology. 



cephalo-dorsal parts of the cortex. There is no apparent reason 

 why this tract should not be homologized with the motor pedun- 

 cles of higher brains. It is not clear to the writer that the fibres 

 terminating in the striatum should be distinguished as basal 

 fore-brain bundle in lower animals unless the same kinds of 

 fibres in higher brains be distinguished within the motor pedun- 

 cle. This Edinger has, in fact, done. In the present instance 

 the fibres do not all emerge from cells at the same level. 



The dorsal or sensory peduncles enter a dorsal and mesal 

 region and are more disperse and less easily followed. They 

 pass chieflly into the mesal portion of the axial lobe and come 

 into more or less direct connection with cortical regions which 

 for other reasons might be regarded as sensory. 



In Urodela the apparent position of the ventral peduncles 

 is rather farther dorsad relatively by reason of the fact that 

 much of the axial lobe, which in frogs, etc., becomes crowded 

 dorsad by the preoptic structures is, in the urodela, left upon 

 the ventral surface and the base of the prosencephalon in the 

 former is in part the lateral aspect in Urodela. 



It would even seem possible that the dorsal peduncle to a 

 certain extent changes places with the ventral. At any rate the 

 precommissure seems to cross ventrad of the ventral peduncle. 



The cornniisswes of the fore-brain are left out of account in 

 the present discussion. The whole question as to the relation 

 of the calloso-fornix structurs requires special considerations on 

 the widest possible comparative grounds. The fornix, at any 

 rate, is fully represented. The fibres collecting from the hip- 

 pocampal region collect in a strong tract which crosses dorsad 

 of the precommissure, but there is a tract in Anura, at any rate, 

 which passes near the ventricle obliquely caudad to the mammil- 

 lary region. They may be followed in a single perpendicular 

 section of the toad brain for most of their course. There is, 

 therefore, close harmony with the conditions in the Reptilia. 



The Gray Matter of the Thalamus. Edinger treats the 

 gray matter of the diencephalon less extensively than the tracts. 

 The geniculatum is recognized as usual but includes the whole 

 mass of cells in the superficial portion of the region beneath the 



