lyo Journal of Comparative Neurology. 



cells niakes its appearance, apparently connected with the 

 sensory bundle. It is bounded laterad by the optic tracts 

 and dorsad by the taenia thalami. 



Immediately caudad to the chiasm the large cot'pus gcni- 

 culatuin appears upon the ventro-lateral aspects of the thala- 

 mus and occupies a position ventrad to the optic tracts for 

 their whole length. The cells are irregularly scattered and 

 of the fusiform variety. 



Somewhat further caudad there appears a peculiar cluster 

 of deeply staining cells ventrad to the geniculatum. The 

 cells of this nidulus are extremely irregular and quite large, 

 with long branching processes, and they are arranged in no 

 definite direction, yet the apical processes are chiefly turned 

 from the periphery. A part of the cells lying, massed near 

 the surface have a rather fusiform character and seem to con- 

 stitute a distinct portion. This nidulus may be designated 

 as the nidulus prfecinereus, although its homology with the 

 anterior nidulus of the cinereum of mammals remains to be 

 proven. A very similar cluster of cells occurs in reptiles 

 near the crura, as also in the opossum. 



The habena is imperfectly divided into two parts, a 

 ventro-median portion, with smaller cells, giving rise to 

 Meynert's bundle, and a cephalo-dorsal and ectal portion, of 

 larger cells, giving rise to the taenia. The right habena is 

 somewhat larger and is apparently chiefly associated with 

 the fibres of the epiphysis. 



The hypoaria^ or lateral lobes of the cinereum, are less 

 highly develojoed in Lepidosteus than in the sturgeon. They 

 arise caudad to the chiasm as tuberosities of the lateral wall 

 of the infundibulum dorsad to the ventral nidulus of large 

 cells above mentioned. A diverticle ot the infundibulum 

 enters them, and this cavity expands to a spheroidal cavity. 

 The cell structure is similar to that of the tuber. In Lepidos- 

 teus they extend much farther caudad, so as to reach the 

 exit of the third nerve. A rather strong tract enters the 

 caudo-mesad portion w^here it is becoming separated from the 



