I.] THE FROG. 49 



^. The voinerifie teeth; two oval patches situated 

 close together near the middle line, immediately 

 internal to the posterior nares. 



d. The tongue; heart-shaped and projecting freely 

 backwards; its free end is prolonged back into 

 two fleshy cornua. Note its mode of attachment. 



Examine its surface under a hand lens; it is 

 beset by a number of elevations [papillce). 



e. The glottis; a median longitudinal slit, situated im- 

 mediately behind the tongue, on the summit of an 

 elevation of the floor of the mouth {larynx). Pass 

 a probe down it and note that it enters the lungs. 



Occasionally, the mucous membrane at its an- 

 terior end is prolonged into two short papillae, 

 which project forwards and probably represent rudi- 

 ments of the epiglottis. 



2. Close the mouth; dissect away the mylohyoid muscle 

 and examine from beneath. 



a, The larynx: forming a hard prominence in the 

 middle line, between and in front of the lungs. 



I). A series of small muscles will be seen arising on 

 all sides and converging immediately in front of a. 

 Dissect them away on one side ; there will thus be 

 laid bare the hyoid (cf Sect. C. 3. c). Examine 

 this, in relation to the larynx. 



a. Its body ; a plate of cartilage closely applied to 

 the floor of the mouth, immediately in front of 

 the larynx. 



p. Its posterior cornua. That of the exposed side 

 will be seen as a bony rod {thyro-hyal) in close 

 apposition with the outer border of the larynx, 



M. 4 



