THE ALIMENTARY CANAL. 227 
tongue is held to the floor of the mouth by the fold known as 
the frenulum lingua. The frenulum contains parts of the two 
genioglossus muscles, which enter the tongue through it. The 
ventral surface and lateral borders of the tongue are smooth, 
soft, and free from papillae. The 
dorsal surface is raised into papillze 
of various kinds, and has a‘slight 
median longitudinal furrow. The 
caudal part of the dorsal surface is 
softer, redder, and marked with 
papilla of a different kind from 
those of the rest of the tongue. 
From the caudal end a_ small 
median vertical fold, the frenulum 
(or plica) glossoepiglottica passes 
from the dorsal surface of the 
tongue to the cranial surface of the 
epiglottis. 
The papille of the tongue are 
of three kinds. 1. The very num- 
erous filiform papilla (a) (pap- 
ille filiformes); many of them 
are horny and tooth-like, with ~ 
points turned caudad. These are 
most numerous at the middle of 
the free end of the tongue. 2. The 
fungiform papille (4) (papille 
fungiformes) are found scattered 4 
over the surface of the middle of Fic. 95. = tencar: EPIGLOTTIS, 
the tongue caudad of the large “ND OPENING oF Larynx. 
: : @, filiform papille; 4, fungiform 
filiform papilla. They are en- papille: 3’, very large papille at the 
larged at their free ends. “There #93 of the tongue; ¢, circumvallate 
: 5 papille; tonsils; ¢, epiglottis; 7, 
is a prominent row of very lar ge plica aryepiglottica: & arytenoid car- 
ones (6') opposite the circumval- Sages. (Cored wilh mucosa) 
late papillz at the borders of the vocal cords. 
tongue. 3. The circumvallate papille (c) (papille vallate) 
are blunt and each is surrounded by a trench which is bounded 
in turn bya raised wall. They are in two rows of two or three 
