26 ILLINOIS BIOLOGICAL MONOGRAPHS (268 



a ventral portion, which follows the general contour of the labium, and a 

 dorsal mound-like part, which resembles the subgusta in the Orthoptera 

 (Fig. 25). Very often this division is not clearly marked, as in Dampf's 

 figure of the psychid Eumeta and in the noctuid Lycoplwtia margaritosa. 

 The question as to whether it is primary or secondary cannot be decided 

 upon the basis of our meager knowledge of the condition, generally found 

 within the order. It is very possible that the dorsal portion may be homo- 

 logous with the subgusta of the Orthoptera, although the entire structure 

 may represent the hypopharynx, in which case the division must be 

 regarded as secondary. 



The hypopharynx typically bears numerous small setae, whose distri- 

 bution, form, size and number vary greatly within the family, offering 

 excellent generic and specific characters. They are rarely apparently 

 absent, as inRhodophora andXylina or may, on the other hand, cover the 

 entire distal portion of the hypopharynx. Frequently the pubescence does 

 not begin immediately cephalad of the labial palpi, leaving a glabrous area 

 in this region, as in Monima, Epizeuxis, and Platyhypena. The setae may 

 be approximately equal in length, as in Lycophotia margaritosa or longer 

 toward the postpharynx, as in Nephalodes, or shorter in this region than 

 the setae near the labium, as in Sidemia devastatrix. In Phytometra and 

 Chloridea they are longer on the sides of the hypopharj'nx than in the 

 middle. They may be sparse, as in Platyhypena, but are more often very 

 densely distributed. They vary greatly in length, sometimes attaining that 

 of the palpi, as in Cirphis unipunda (Fig. 26), but are most frequently 

 much shorter, like those of Lycophotia margaritosa (Fig. 38), or stout and 

 very minute as in A gratis ypsilon (Fig. 44). In Lycoplwtia infecta they are 

 so short that the surface of the membrane appears granular. No correla- 

 tion between these various conditions and the feeding habit has been dis- 

 covered. The function of these setae is probably essentially protective, 

 although they may serve as sensory organs. 



The epipharynx of lepidopterous larvae is membranous and continuous 

 with the labium on its ventral and lateral margins and with the post- 

 pharynx at its dorsal end (Fig. 13). It bears a pair of narrow longitudinal 

 sclerites, the tormae, which lie entad of the ends of the ch'peo-labral suture. 

 Three stout primary setae are borne on each side in the membrane near 

 the ventral margin. A fourth minute seta figured by Dampf in the psychid 

 genus Eumeta has not been found in the Noctuidae. No modifications of 

 the epipharynx, such as those which occur in the leaf-miners, have been 

 encountered in the family. Neither the form of the torma nor the position 

 of the setae is subject to marked variations. 



