2 Mangan, MaxillidtE in Larvce of DytiscidcE. 



{Fig. I, a\ but in reality it is merely a deep groove on the 

 surface, the opposite margins of this furrow being closely 

 approximated but not united. The proximal region 

 leading from the opening at the base of the mandible 



Fig. I. The mouth parts of the mature larva of Dytisctis 

 iiiarginalis seen from above. Labrum and clypeus removed. 



rt, left mandibular canal ; an, left antenna ; /', tjasal opening of 

 left mandibular canal ; e, ventral wall of duct leading from 

 mandible to mouth cavity ; f, the mouth cavity ; la, the labium ; 

 ni, the left maxilla ; ph, the pharynx ; pr, backward process of 

 mouth cavity ; r, interlocking ridge on ventral side of mouth 

 opening ; x, processes homologous with maxillulre, the right 

 process raised from its normal position. x 11. 



{Fig. I, b) to the mouth cavity is formed of two opposed 

 grooves situated respectively on the epipharynx and on 

 the ventral surface {Fig. i, c) of the mouth. These 

 grooves are held closely in contact by the interlocking 



