BRANCHIAL SENSE ORGANS IN ICHTHYOPSIDA. 153 
Fic. 4.—Transverse section of embryo of Rhodeus amarus, showing 
olfactory nerve and thickening both fused with skin. Letters as before :— 
f. or. Brain. Z. ¥, oc. 2, cam. luc. 
Fie. 5.—Transverse section through fore-brain and olfactory organ of an 
embryo T. ocellata. Combined from several sections. Shows olfactory 
nerve and ganglion fused with thickening and connected with brain. Letters 
as before. 4%. a, oc. 2, cam. luc. 
Fic. 6.—Somewhat horizontal section through mid-brain, showing nerve of 
ciliary ganglion (z. c. g/.) just fusing with skin. T.ocellata. Z. 8, oc. 2, 
cam. lue. 
Fic. 7.—Low power view of same section. Z. c, oc. 2, cam. luc. 
Fies. 8 and 9.—High and low power drawings respectively of a somewhat 
horizontal section through fore and hind-brain. Shows ciliary ganglion rudi- 
ment (ce. g/.) and its primitive branchial sense organ (p. dr. 0.). The ganglion 
is in course of formation from the epiblast. . dr. Fore-brain. 4. dr. Hind- 
brain. Torpedo ocellata. Z.p and 4, oc. 2, cam. luc. 
Fic. 10.—Horizontal section through a young Torpedo embryo, showing 
ciliary ganglion still fused with its sensory thickening. Also shows motor- 
oculi nerve (111). c¢. gl. Ciliary ganglion. p. br. 0. Primitive branchial sense 
organ. 1. Motoroculi.  G. gi. Gasserian ganglion. Ay. cl. Hyoid cleft. 
m. br. Mid-brain. 4. c. Heady-cavity. f g/. Facial ganglion. Z. a, oc. 2, 
cam. luc. 
Fie. 11.—Drawing under high power of ciliary ganglion and its primitive 
sense organ of the preceding section. Late stage, but still intimate fusion 
with skin. Also origin of suprabranchial nerve of ciliary ganglion (opth. 
profund) from skin. Suprabranchial nerve (s. d7.2.). Z.¥F, oc. 2, cam. luc. 
Fies. 12 and 18.—Similar drawings to Figs. 10 and 11 respectively. 
Letters as before. g/. g/. Glossopharyngeal ganglion. 
Fic. 14.—Horizontal section through mid-brain and anterior portion of 
hind-brain. Shows course of fifth nerve, which lies just under skin, but is 
not yet fused with it. No ganglion yet present. T. ocellata. Z. c, oc. 2, 
cam. luc. 
Fie. 15.—Fifth nerve fused with its sensory thickening (p. dr. s. 0.), and 
proliferation of Gasserian ganglion from the skin. G. g/. Gasserian ganglion. 
T. ocellata. Z. c, oc. 2, cam. lue. 
Fie. 16.—Similar figure to preceding one. T.ocellata. Z. c, oc. 2, cam. 
luc. 
Fic. 17.—Section through hind and fore-brain, Shows Gasserian ganglion 
just before its separation from the skin. T.ocellata. Z. a, oc. 2, cam. luc. 
Fic. 18.—Small piece of a horizontal section of a Torpedo embryo. Shows 
hyoid prebranchial nerve (pd. x.) lying in epiblast and not yet separated from 
it. G. gl. Gasserian ganglion. /f. gi. Facial ganglion. 
VOL, XXVI.—NEW SER L 
