98 PROCEEDINGS OF THE NATIONAL MUSEUM vol. ii8 



placed in Stenoma, of which one {S. curiata) is a synonym, together 

 with four new species encountered during the course of this study. 

 Unfortunately, as is the case for most species of Stenomidae, host 

 plant records and other biological data are lacking; however, I hope 

 that field explorations planned for the near future will correct this 

 situation at least partially. 



This research was aided by a grant from the National Science 

 Foundation. The drawings were made by Mr. Andre Pizzini and the 

 photographs by Mr. Jack Scott, staff photographer. 



Genus Lethata, new genus 



Type-species: Stenoma trochalosticta Walsingham, 1913, in Godman 

 and Salvin, Biologia Centrali-Americana, vol. 42 (Lepidoptera- 

 Heterocera, vol. 4), p. 177. 



Head with spreading lateral tufts. Labial palpus long, recurved; 

 second segment thickened with appressed scales; apical segment acute, 

 shorter than second. Forewing with costa arched, apex rounded, 

 termen obliquely rounded, tornus rounded; 12 veins, all separate: 

 2 from before angle, 3 from angle, 4 approximate to 3, 7 to termen, 8 

 to apex. Hindwing broader than forewing; 8 veins: 3 and 4 connate, 

 6 and 7 connate. Abdomen of males with strong, eversible pair of 

 hair-pencils contained in elongate cuplike pocket on fii*st sternum 

 (Fig. 3a). 



Male genitalia: Uncus short, more or less recurved; tegumen some- 

 what narrowed in the area of the uncus and gnathos; gnathos fused, 

 setiferous; harpe simple, bifurcate setae present or absent; anellar 

 lobes symmetrical or asymmetrical; aedeagus with or without cornuti. 



Female genitalia: Ostium bursae sclerotized; ductus birrsae sclero- 

 tized to inception of ductus seminalis, membranous beyond; corpus 

 bursae membranous, with two dentate signa connected by narrow, 

 weakly sclerotized band. 



This genus is distinguished readily from all other genera in the 

 famUy Stenomidae by the setiferous gnathos and the two dentate 

 signa connected by a weakly sclerotized band in the corpus bursae. 



Although exact relationships are virtually impossible to ascertain 

 at this time, the general structure of the genitalia in the genus Lethata 

 indicates an affinity with Gonioterma Walsingham. 



One of the most striking features of the family Stenomidae is the 

 presence of modified setae on the harpes of the male genitalia. In 

 the genus Lethata, however, apparently this character is not consistent. 

 Initially it was thought that modified setae did not occur in the genus 

 at all, but examination at very high magnifications revealed the tips 

 of the setae to be bifurcate in some species. A seta of this type has 



