Herrick, Morphology of Brain of Bony Inshcs. 357 



its way the dense nidulus of multipolar cells which is so con- 

 spicuous a feature of the ventricular aspect of the thalamus. 

 The ventro-mesal portion of the peduncles proper seems 

 to have a different course, both in the cerebrum and the 

 thalamus, from the dorso-lateral portion. The former pass 

 cephalad and mesad and give rise to the thin disperse tract 

 which separates the lateral from the central lobe. Many of 

 its fibres cross in the callosum. The latter forms the con- 

 spicuous peduncular tract occupying the posterior part of the 

 central lobe. Its fibres appear to supply the dorsal and 

 caudal parts of the axial lobe. 



PLATE XXIV. 



Horizontal longitudinal sections through the entire brain of the 

 drum, HafJoidotiotus. Those parts especially referred to in this instal- 

 ment are, for the most part, named on the plate. The left side is at a 

 slightly more ventral level than the right. 



Fig. 1. Section through the olfactory lobes and corpus fornicis. 

 The radix lateralis is easily followed throughout its entire length from 

 the lateral aspect of the pero to the hippocampal lobe. The radix 

 mesalis arises in the pes, and, curving ventrad and then dorsad, appears 

 cepalo-ventrad of the axial commissure as a circular bundle. 



Fig. 2. Section at the level of the axial commissure (see text) and 

 callosum. 



Fig. 3. Section above the level of the pr?ecommissura, whose tracts 

 are nevertheless seen in the section. The index letters indicate regions 

 from which the detailed drawings of histology were taken as given on 

 Plate XXV. 



Fig. 4. Section near the dorsal surface of the cerebrum. The 

 figure illustrates the structure of the volvula and cerebellum. Compare 

 Fig. 7, Plate XXV. 



PLATE XXV. 



Fig. 1. Highly magnified portion of the pero entad of the glom- 

 erules. There happen to be no instances of direct connection of cells 

 with glomerules in the field. 



Fig. 2. Pyramidal kinesodic cells from central lobe (see Fig. 3, 

 Plate XXIV). 



Fig. .). Superficial part of lateral lobe to show epitiielium. The 

 sesthesodic cells of that region are cut transversely. 



Fig. 4. Peculiar cells in tract e, Plate XXIV. 



Fig. o. Portion of cuneus to show both sorts of flask cells. The 

 outermost properly are associated with the cells of the lateral lobe. 



