DEVELOPMENT OF EAR AND ACCESSORY ORGANS IN FROG. 547 
EXPLANATION OF PLATES XXXIV & XXXV. 
Illustrating Mr. Francis Villy’s paper on ‘‘ The Development 
of the Ear and Accessory Orgaus in the Common Frog.” 
Alphabetical List, of Reference Letters. 
A. C. Annular cartilage. 4.C. H. Anterior cornu of the hyoid. dm. A. 
Ampulla of the anterior vertical canal. 4x. C. Anterior vertical canal. 
Au. C. Auditory capsule. dw. #. Auditory epithelium. du. G. Auditory 
ganglion. du. J. Auditory invagination. dw. N. Auditory nerve. Aw. V. 
Auditory vesicle. 2. Basi-hyal cartilage. 2B. C. Body-cavity. Br. Brain. 
Br. A. 1, 2, 3, 4. Branchial arches. Br. C. 1, 2, 3, 4. Branchial clefts. C. 
Cerebellum. Cd. Cerebral hemispheres. Cd. Choroid plexus. Ch. Cochlea. 
Ch. 1. Lagena. Ch. 2. Pars neglecta. Ch. 3. Pars basilaris. C/. Colu- 
mella. Cr. Cornea. D. dA. Dorsal aorta. #. Hye. Hp. A. Epithelium 
of the two anterior ampulle. 2p. C. Hpicoracoid. #. Kustachian tube. 
F, Fenestra ovalis. G. G. Gasserian ganglion. G. WV. Glossopharyngeal 
nerve. Gu. Gullet. Hé. Hind-brain. “Ho. A, Ampulla of the horizontal 
canal. Ho. C. Horizontal canal. Hp. Hypoblast. Hw. Humerus. Hy. A. 
Hyoid arch. Hy. M. Hyomandibular cleft. Jz. Interstapedial cartilage. 
Ir. Iris. K. Kidney. JZ. Lens. Md. Mandibular arch. Ms. Meckel’s 
cartilage. Mo. Mouth. Ms. Mesostapedial cartilage. Ne. Nervous layer of 
epiblast. 1. G. Neural groove. Wo. Nose. V+. Notochord. OJ. NV. Olfac- 
tory nerve. Op. /. Optic lobes. Op. N. Optic nerve. O¢. #. Outer layer of 
epiblast. Pa. pt. Palatopterygoid bar. Pe. Precoracoid. Pe. 1. Perilym- 
phatic canal (connected with the lagena). Pe. 2. Perilymphatic canal (con- 
nected with the teg. vasc.). 2. V. dA. Ampulla of the posterior vertical 
canal. P&P. V. C. Posterior vertical canal. Q. Quadrate cartilage. 2. Re- 
cessus labyrinthi. §.Scapula. Sac. Sacculus. §. 4. Septum of anterior 
vertical canal, outer fold. §. 4.1. Septum of horizontal canal, upper fold. 
S. H. 2. Septum of horizontal canal, lower fold. §. P. 1. Septum of pos- 
terior vertical canal, outer fold. S. P. 2. Septum of posterior vertical canal, 
inner fold. S¢. Stapes. S¢x. Sternum. Sz. Suprastapedial cartilage. Sw. s. 
Suprascapula. 7. Tail-muscles. 74. Thymus. Zy. Tympanic cavity. U. 
Utriculus. V. Vagus. dz. Third nerve. 
These figures are all more or less diagrammatic in different ways, but in all 
the general outlines are as nearly correct as possible, for they are all taken 
from camera drawings. The shading is diagrammatic, and no attempt has 
been made to show cells, except in a rough way in the younger stages of the 
auditory epithelium. In other organs, such as the young brain, any marking 
