INTRODUCTION. 



behind the antennae and bearing the eyes and ocelli, and the clypeus, 

 which constitutes the front of the head and is so distinctive of the 

 Lepidoptera by reason of its large size. The labruni is very minute 



Fig. 1. — Head of a Lepidopterous insect from above and from the side. 



(From Packard's Guide, p. 232.) 



at. Antennas. ec. Epicranium. 



c. Clypeus. oc. Occiput. 



e. Eye. m. Mandibles. 



I. Labruni. nix. Proboscis. 



m.p. Maxillary palpi. l.p. Labial palpi. 



o. Ocellus. 



and concealed by the clypeus ; the labium is small, short, and tri- 

 angular ; and the mentum nearly obsolete, its place being supplied 

 by the maxillae, which form a long grooved proboscis. In some 

 important papers by A. Walter*, it is shown that the maxillary 

 palpi, whilst obsolete in some species, are from 1- to 6-jointed in 

 those that possess them ; Micropteryoe has the largest number of 

 joints, 6 ; in the Tineas and Tortrices the number is very variable ; 

 in the Pyrales 4, in the Noctues generally 2, but sometimes 3 ; 

 in the Bombyces 1 or 2 ; in Rhopalocera, Sphingidce, and most 

 Geometridce, 1. 



Mandibles exist in Micropteryx and a few other Tineidce ; 

 M. aruncella and anderschella have them toothed and capable of 

 gnawing, whilst in M. purpurella and semipurpurella they are not 

 denticulated ; in these the maxillae have two palps, whilst in the 

 higher Lepidoptera the inner palps are reduced. In the lower 

 forms of Micropteryx, which connect the Lepidoptera with the lower 

 Hymenoptera or Neuroptera, the free palps and typical ligula of the 

 lower insects are present, the ligula being formed by the fusion of 

 the inner palps into a short tubule open externally, a short hypo- 

 pharynx being present on the inner wall. In the higher Lepi- 

 doptera the mandibles are rudimentary and consist of horny tubules ; 

 the labial palpi are generally well developed and consist usually of 

 three joints, their shape being of great use in generic distinction ; 

 they may, however, be reduced to two joints or to one, or be entirely 

 absent in the families in which the mouth-parts are obsolete. 



* Jena. Zeit. Nat. xviii, pp. 121-173 (1884;, and Jena. Ges. 1885, pp. 19-27. 



