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 labrum is very minute 



...".'' 



Fig. 1. Head of a Leptdopteroua iusivt fr.mi alum- and from the side. 



(From Packard's Guide, p. li: '.'_'. ) 

 at. Antennir. ec. Epicranium. 



c. Clypeus. oc. Occiput. 



e. Eye. ///. Mandibles. 



I. Labrum. mx. Probox-is. 



m.p. Maxillary palpi. /./>. Labial palpi. 

 o. Ocellus. 



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

 angular: and the mentmn nearly obsolete, its place lie ing supplied 

 by the max ilia-, 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; Micro^t, ///./ has the largest number of 

 joints, G; in the Tineas and Tort rices the immlier is very variable ; 

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

 in the Bombyces 1 or "2 ; in Rhopalocera, Sphinyi<l<r, and most 

 Geometridce, 1. 



Mandibles exist in J//r/vy >/<///'' and a few other 7V//./V,/-; 

 M. aruiifcUit and niH/fw/nftn have them toothed and capable of 

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

 denticulated ; in these the maxilla) 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 

 //i/niaioptera 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. 



