104 Journal of Comparative Neurology. 



The next instalment will be occupied with the mesencephalon 

 and cerebellum and embryological data. 



PLATE V. 



Transections of the brain of the horned toad, Phrynosonia coronata. (See 

 page 87.) 



Fig- J . Section at the union of olfactory tuber and cerebrum. 



Fig. 2. Section where the dorsal cornu of the ventricle unites with the ven- 

 tral. The arcuate fissure, separating the intraventricular and fronto-median 

 lobes, is just appearing. 



Fig. J. Section near the cephalic limit of the fronto-median lobe. tr. a., 

 callosal fibres. 



Fig. 4. Section at the callosum. oc. fias., nucleus sphericus in occipito- 

 basal lobe ; trt'u., central lobe; ped., peduncle tracts. The chiasm and infra, 

 commissure appear below. 



■^'g'- 5- Section at the hipjjocampus corammissure, Hip. c. 



Fig. 6. Section near caudal limit of the hemispheres, tr. h., fornix tract 

 spreading out upon the occipital region. 



Figs. j-g. Sections through the optic lobes. 



Figs. lo-ij. Section.' through the medulla and cellebellum to show the rc- 

 troflection of the latter. Di%'., V. IV., diverticle of the fourth ventricle 



PLATE VL 



Fig. I. .\n oblique longitudinal section through the brain of Tropidonctus. 

 (l) central lobe, (2) fornix, (3) hippocampus, (4) longitudinal fasciculus, (5) lem- 

 niscus, (6) corpus posterior, (7) cerebellum, (8) postplexus, (9) medipeduncle 

 cerebelli, (10, ii) niduli of thalamus, (12) optic tracts, (13) tract of the supra- 

 commissure; (14) precommissure, (15) tracts from the same. 



Fig. 2. Part of another section of the same series at a higher level, {a) 

 tract of supra-com., (/') corpus fornicis, (r) geniculatum, [d) lateral ventricle, [e) 

 pre-com., (/") tract to sphericus, [gli] tracts to pre-com., (/) supra-com., (y) pa- 

 raphysis, {k) fornix. 



Fig, J. Portion of longitudinal section of blue racer, (a variety of the 

 black snake,) illustrating relation of hippocampus commissure to plexus and the 

 peduncles. 



