154. JOHN BEARD. 
PLATE IX. 
Fic. 19.—Transverse section through hind-brain of a Torpedo embryo. 
Facial nerve (v1I) just on poiut of fusion with its sensory thickening. Gill- 
cleft (hyoid) just about to form. Z. c, oc. 2, cam. luc. 
Fie. 20.—A similar section. Facial nerve just fused with skin, and its 
postbranchial (p. ~.) passing on to muscles of cleft. Z. a, oc. 2, cam. luc. 
A later stage of facial ganglion in Fig. 42. 
Fic. 21.—Facial ganglion leaving skin, and still connected by two supra- 
branchial nerves (s. 6. z. 1 ands. 6. ”.2). Z. D, oc. 2, cam. lue. 
Fic. 22.—Horizontal section of a Torpedo embryo. Facial ganglion fused 
with auditory, but line of demarcation is obvious. Facial has just left the 
skin, and is leaving a suprabranchial nerve (s. 0. ~.) behind it. 
Fig. 23.—Part of a transverse section through the auditory region of a 
Torpedo embryo. Auditory nerve (vi11) not yet fused with auditory thicken- 
ing (au. 0.). Z. F, oc. 2, cam. luc. 
Figs. 24 and 25.—Auditory just fused with auditory thickening, and 
ganglion proliferating. Letters as before. T.ocellata. Z.¥, oc. 2, cam. luc. 
Fic. 26.—Low power drawing of a horizontal section, such as the two 
preceding figures form part of. 
Fie. 27.—Transverse section, rather oblique, through hind-brain of a frog 
embryo. Shows auditory nerve and thickening on one side, and vagus nerve 
and ganglion on the other. aw. x. Auditory nerve. vg. Vagus nerve. vg. gl. 
~ Vagus ganglion. Z. A, oc. 2, cam. luc. 
Fig. 28.—High power drawing of auditory portion of preceding. Shows 
auditory nerve not yet separated from skin. Z, ¥, oc. 2, cam. luc. 
Fie. 29.—Transverse section through auditory region of an Elasmobranch 
embryo. Shows auditory ganglion and auditory thickening intimately fused 
together. Auditory involution as yet only partial. _ 
Fie. 30.—Similar section under low power. Auditory involution complete. 
Fic. 31.—Highly magnified drawing of auditory portion of last section. 
Shows intimate fusion of ganglion and thickening, and proliferation of cells 
of thickening into ganglion. Many nuclear figures near proliferating portion. 
Fic. 32.—Transverse section through hind-brain of a Torpedo embryo. 
Shows glossopharyngeal nerve (1x) just fused with its primitive branchial 
sense organ (p. br. 0.). Z. c, oc. 2, cam. luc. 
Fic. 33.—Similar section to preceding. Vagus nerve (x) just before 
fusion. Z. c, oc. 2, cam. 
Fic. 34.—Similar section. Vagus nerve just fused with its thickening. 
Postbranchial branch (p. 2.) passing on to muscles of cleft. Z. D, oc. 2, 
cam. 
Fics. 35 and 36.—Portions of similar sections to preceding. Portions of 
