4 ARKIV FÖR ZOOLOGI. BAND 6. NiO 7. 



pointed and less curved; the median pair is slender and bent 

 downwards and backwards at the top Jike a hook; the other 

 two curve almost at the base downwards, backwards and 

 towards each other, so that they are visible only on ventral 

 view. 



From the structure of the labrum it is evident, that, 

 besides its original function, to form the roof of the mouth 

 opening, it is highly adapted to the purpose of assisting the 

 mandibles in their work viz. to detach portions of the pa- 

 ren chy ma of the leaf. 



The mandibles (Figs. 12 & 13, Pl. II) are strongiy 

 chitinous and dark coloured, sligtly longer than they are 

 broad at the base; they have a double terminal tooth, one 

 above the other. The upper side of the mandible is almost 

 even and horizontal, sloping only slightly downwards towards 

 the inner edge; the ventral one, on the other hand, slopes 

 downwards distinctly towards the middle. The upper tooth 

 is shghtly stouter than the lower one, with thin inner edge, 

 which near the base rises to a low, blunt molar. The lower 

 tooth bends slightly downw^ards and has a blunter median 

 edge. Between the two teeth there is a deep groove. 



The mandible bears two fine, pointed hairs, which are 

 inserted close together at the exteriör edge, a little behind 

 the middle. 



The antennse (Fig. 14, Pl. I) are greatly reduced and 

 appear as low, thin-walled areas, which scarcely project above 

 the surface; they bear an oval, thin-walled and finely concen- 

 trically striated appendage, on the exteriör side of which 

 4 — 5 straight hairs are placed. 



The statement of Hegeer that the antennse are two- 

 jointed [3. p. 431 must be caused by some mistake. 



The max ill 3e (Fig. 8, Pl. II): the lobus internus is 

 conical, with a comb of long and rather slender bristles along 

 the inner edge; the maxillary palps aj:e two-jointed; the 

 two joints form together a short conical projection, broadly 

 rounded at the top, where 4 — 5 small sensorial cones are to 

 be found. 



The labium (Figs. 9 & 14, Pl. II) is broad and ton- 

 gueshaped, with very soft cuticle; at the edge and on the 

 inner side it bears numerous rows of minute cuticular teeth, 

 which point backwards; the labial palps are single-jointed, 



