Herrick, Braifi of Certain Reptiles. I39 



Fig. J. Section of same brain in chiasm region ; Ep. epiphysis ; II. hab- 

 ena ; /«/. H. infra-habena ; Meynrt. n. Meynert's nidulus ; gen. geniculatum ex- 

 ternum, that portion forming a pseudo-epithelium at surface cephalad of optic 

 tracts; suhth. probably horaologue of internal geniculata grouped with others 

 as subthalamicus niduli ; vp. ventral peduncles ; inf. infracommissural fibres ; 

 X, ventricular gray. 



Figs. 4-7. Sections from frog brain at different levels ; nid. V. mesenceph- 

 alic nidulus of trigeminus; ped. nid. peduncular nidulus or accessory nidulus of 

 the third nerve; corp. p. corpus posterior; Med. ped. cer. middle peduncle 

 of cerebellum which decussates after exit from the outer layer of the cerebel- 

 lum and passes through and about the corpus posterior and, passing cephalo- 

 ventrad, enters the ventral peduncular region, losing itself in tbe locus niger ; 

 Lem. lemniscus tract, fibres which pass from the inner fibre layer of the tectum 

 to a region near the exit of the fifth nerve. 



Fig. 8. Cells from the nidulus ruber. The fibres seen are from the com- 

 missura horizontalis. 



Fig. g. Longitudinal section of frog brain. Compare Plate XVII; lat. tub. 

 lateral expansion or lobe of the olfactory tuber, near which the radix originates ; 

 Corp. dent, the dentate nidulus. 



Fig. 10. A similar section well mesad ; /«/%: infra-habena nidulus ; Meyn. 

 n. Meynert's nidulus ; Br. brachium ; inf. infundibulum region or tuber ciner- 

 eum ; x, thalamic nidulus in the peduncle bundle. 



Fig. II. Cell from the intra-ventricular lobe of frog. 



Fig. 12. Portion of the gray matter of the cerebrum of a toad about the 

 cephalic end of the olfactory radix. 



Fig. /j>. Result of injection of Menopoma brain, fine meshwork of the 

 gelatin emerging from blood-vessles. Are the cavities pre-existant or is this 

 structure simply due to the peculiar texture? 



PLATE XVII. 



A series of longitudinal sections of the brain of the frog. B.p.g. Basal 

 peduncular ganglion or part of striatum with fibres of the ventral peduncles; 

 Olf.n olfactory nerve; ^/. glomerulary layer; ^fl!«^. ol. specific ganglia of olfac- 

 tory tuber; Chias. chiasm; Mamm. mammillary body; Supr. c. supracommis- 

 sure M. n. Meynert's nidulus; Gen. geniculatum; n. 0. p. nidulus of the post 

 optic region in the course of the ventral peduncles; Corp. forn. corpus fornicis; 

 Br. brachial tracts; tr. opt. ceph. cephalic optic tract; tr. opt. caud. caudal 

 optic tract; P. c. Post. c. postcommissure; Sylv. c. Sylvian commissure or tectum 

 commissure; d. I. f. dorsal longitudinal fasciculus; Hyph. hypophysis; Dors. 

 ped. sensory or dorsal peduncles; Pre. o. c. i. and Pre.o.c. 2 Preoptic cinerea in 

 two portions separated by a tract or space; Pre. 0. n. preoptic nidulus. The 

 series is from a lateral level to the centre. 



PLATE XVIII. 



Figs. 1-8. A series of horizontal sections through the brain of Necturus. 

 Haematoxylin preparations. 



Fig. I. Section at the level of the supracommissure. Prepar. preparaphy- 



