BUCCAL APPARATUS OF INSECTS. 



iQ to pierce the skins of animals or the vessels of plants, are 



the representatives of the 

 mandibles and the maxillae 

 extremely elongated. In 

 \_ / Sr ' * those Rhynchota which live 



at the expense of other ani- 

 mals, the proboscis is usual- 

 ly very firm, and folds into 

 a semicircle under the head. 

 Among those which are 

 nourished by sucking veget- 

 ables, on the contrary, it is 

 \. nearly always thin, and is 

 laid when in a state of rest 

 against the lower side of 

 the thorax, between the feet. 



Its length is sometimes so considerable, that it passes backwards 

 behind the posterior extremity of the abdomen. 



674. Amongst the Flies, also, the proboscis, which is some- 

 times soft and retractile, sometimes horny and lengthened, repre- 

 sents the under lip, and often bears a sort of double disc at its ex- 

 tremity, which is regarded as representing the labial palpi ; a longi- 

 tudinal channel occup'es its upper si !e, which incloses the setce; 



FIG. 420. BUCCAI, APPARATUS OF AN 

 HEMIPTEROUS INSECT. 



FIG. 421. NXME-STHINA TONGIROSTRIS. 



ose number varies from two to six, their analogues amongst the 

 insects being the mandibles, the maxillae, the labrum, 



