Herkick, Morpliology of Nervous System. \z^n 



than the left. The bundles pass cephalad and mesad to the 

 fibres of the oculo-motor, and gradually pass dorsad, and at 

 the point of communication of the ventricle of the lobus 

 infundibuli with the mesencephalic ventricle they lie adja- 

 cent to the epithelium. These bundles terminate cephalad 

 to the anterior commissure in the ganglion habenulae. 



"The ganglion habenulae is but slightly difterent from 

 that of the teleosts, except for the pronounced asymmetry, 

 which is responsible for the unequal development of Mey- 

 nert's bundles. Each ganglion consists of a central collection 

 of granular substance, which in cross-sections appears fibrous 

 at the periphery. The fibres converge to the median surface 

 of the ganglion and form a commissure uniting the ganglia. 

 The central substance is surrounded by several layers of 

 granular cells, which greatly resemble those of the lobus 

 infundibuli. The plasmatic body surrounding the large 

 round nucleus is more highly developed, and its produced 

 poles are radial to the surface. These cells send their pro- 

 cesses into the central substance, even to the middle of the 

 ganglion. The dorsal surface of the ganglion has a thinner 

 layer of granular tissue than the ventral, which is separated 

 from the central substance by a layer of longitudinal fibres. 

 The chief portion of these fibres belongs to Meynert's bundle; 

 the smaller portion collects from the ventral portions of the 

 brain walls. The radial fibre systems which spring from the 

 granular cells of the ventral layer are divided into small 

 bundles by the fibres just described. In the feebly developed 

 left ganglion the ventral granular cells lie directly upon the 

 central substance. The fibres of Meynert's bundle, as well 

 as the fibres of the ventral part of the brain walls, are dis- 

 persed in the central tissue of the left ganglion." 



Lateral ventricles . — The lateral ventricles are not absent, 

 as Wilder supposed, nor are they merged in the olfactory 

 ventricles, as stated by others. (') Fig. i, Plate XI, taken at a 



I Sanders, op. cit., p. 768: "The cerebral lobes homologize the corpora striata. 



