6 TUCKERMAN. [VoL. Il. 
EXPLANATION OF PLATE I. 
List OF REFERENCE LETTERS. 
c.e. Columnar epithelium. g.. Gustatory pore. g/. ad. Duct of serous gland. 
m.m. Mucous membrane. Z. Elongated papilla. f. e. Pavement epithelium. 2. £. 
Papillary processes of mucous membrane. ». Ridge. s. e. Stratified epithelium. 
s. p. Secondary papillz. ¢. Trench. 7. 4. Taste-bulb. 7. 6’. Taste-bulb of outer wall 
of trench. 7¢. 4.’ Taste-bulb undeveloped or of low type. 
Fic. 1.— Vertical section through one of the circumvallate papillz. (x 100 
diam.) 
Fic. 2. — Vertical section through the base of the same papilla, showing over- 
hanging side with four lowermost tiers of taste-bulbs. (Xx 480 diam.) 
Fic. 3. — Vertical section through the left lateral circumvallate papilla. (xX 125 
diam.) 
Fic. 4.— Horizontal section through the lower part of one of the circumvallate 
papillz, representing the taste-bulbs arranged ina zone. /. d. Ducts of the serous 
glands which open into the trench at this level. (xX 160 diam.) 
Fic. 5.— Vertical section through a fungiform papilla of the mid-dorsal surface of 
the tongue, showing a single taste-bulb at its upper part. (XX 400 diam.) 
Fic. 6.— Vertical section through a fungiform papilla of the posterior dorsal sur- 
face of the tongue, which is probably undergoing transition to the circumvallate type. 
(X 480 diam.) 
Fic. 7.— Vertical section through a fungiform papilla of the anterior lateral dor- 
sal surface of the tongue of a pig. (X 200 diam.) 
