﻿I.] THE FROG. 163 



Examine from the side. 



c. The mouth; surrounded by a protractile bell- 

 shaped suctorial tip, and utilized for purposes of 

 adhesion, in place of the suckers which are now 

 disappearing. 



Cf. the movements of the living larva. 



;//. The development of the operculum. Look for larva? 

 intermediate between k and /. Examine from the 

 side. 



The operculum will be seen arising, on either 

 side, immediately in front of the external gills, as a 

 backwardly-directed fold of the second (Jiyoid) 

 visceral arch. 



n. The larva at a later stage than I ; conspicuous by 

 the great length of its tail and the absence of 

 external branchiae. Examine from beneath. 



a. The body generally ; clad in a thin transparent 

 integument, elegantly pigmentcd in black and 

 gold. 



(3. The mouth ; still increasing in size, the cir- 

 cum-oral papilke becoming more marked. 



y. The suckers ; still further reduced and repre- 

 sented by two small vestiges. 



8. The intestine; visible through the body-wall as 

 a greyish coiled tube of large calibre. 



e. The amis (cloacal orifice); median and ventral, 

 situated at the base of the tail on the summit of 

 the pointed posterior extremity of the trunk 

 (cf. side view). 



. The hind-limbs ; minute papillate outgrowths of 

 the body- wall, at the sides and a little in front of e. 



I I 2 



