II HR KICK. Morp/io/ooy of N'crvoi/s Syslc/i/. i8l 



corpus callosum; ac', ac", (ic"\ frontal, parietal and occipital portions 

 of pra'commissura; /., fornix; /./., tract from the tienia thalami into the 

 thalamus. 



Fig. S. Section somewhat cephalad to Fig. 9. //., habena; M., 

 nidulus Mevnerti; .\'., substantia nigra; />'., nidulus of the substantia 

 nigra; P., peduncles. 



Fig. 9. Transection through optic lobes and infundibulum of the 

 lizard. c.S., commissura Sjlvii; F.i ., postcommissura; /., pedunculi; 

 of Jr., optic tracts. 



Fig. 10. Median longitudinal section of an embryonic black-snake 

 brain, (see Fig. 5), to show the relation of the epiphysis to the habena, 

 membranes, and skull. 



Fig. 11. Section through the cerebellum of one of the same set of 

 embryos near the caudal extremity, to illustrate the proliferation of 

 Purkinje's cells. (Compare Fig. 14.) 



Fig: V2. Section through the same brain at the base of the cere- 

 bellum at the exit of the trigeminal nerve. 



Fig. 13. Similar section at the exit of the eighth, which, by reason 

 of its slight obliquity, also displays the course of the seventh nerve. 



Fig. 14. A portion of a section adjacent to that of Fig. 11, at the 

 angle of the ventricle, illustrating, as is supposed, the proliferation of 

 Purkinje's cells from cells associated with the ventricular epithelium. 



Fig. 15. Pyramidal cells from the motor region of the brain of a 

 lizard. 



PLATE XIII. 



Figs. 1-8. Transections through the brain of the Gar-pike, Lepi- 

 dosteus. 



Fig. 1. Olfactory lobe. t./., cephalad projection of the lateral 

 ve^ntricle, roofed over by the velum. 



Fig. 2. Transection at the callosum, c.c. v. I., lateral ventricle; 

 III., membranous roof of the ventricle corresponding to the mantle; a./., 

 axial lobe of the cerebrum; f.M., foramen of Monro; gl., remnant of 

 the glomerular layer of the olfactory; n 1, olfactory nidulus beneath the 

 aqueduct of the olfactory. 



Fig. 3. Transection back of the chiasm. A mesad protuberance 

 of the axial lobe corresponding to a part of the striatum is separated by 

 projections of the ventricle. The aula is partly contluent with the ven- 

 tricles, v.t., spur of the posterior cornu passing cephalad. In the con- 

 necting portion uniting the thalamus and hemispheres some evidence of 

 the trenia thalami was detected. 



Fig. 4. Transection at the level of the habense. The lateral ven- 

 tricles have completely circumscribed the axial lobe, c.g.c, corpus 

 geniculatum externum; «, lateral nidulus of the thalamus; //v., hypo- 

 physis; ?/.A/., nidulus Meynerti; /. ^1/., foramen of Monro. 



Fig. 0. Transection through the posterior commissure. A portion 



