[.] THE FROG. 163 



Examine from the side. 

 €. The mouth; surrounded by a protractile bell- 

 shaped suctorial lip, and utilized for purposes of 

 adhesion, in place of the suckers which are now- 

 disappearing. 



Cf. the movements of the living larva. 



in. The development of the operculum. Look for larvae 

 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 {hyoid) 

 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 pigmented in black and 

 gold. 



y8. The mouth; still increasing in size, the cir- 

 cum-oral papillae 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. 



€. The anus (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). 



t,. The hind-limbs ; minute papillate outgrowths of 

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



II — 2 



