18 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 122 



Described from the male holotype: "Colombia: San Jaoquin, 

 Dept. Santander, 30.VIIL65 (W. D. Duckworth)." 



This species is very closely related to the following one, obscura; 

 however, the differences in shape and armament of the anellar lobes 

 plus the number of oornuti and placement of lateral spines in the 

 aedeagus readily distinguish between the two. 



Lethata obscura, new species 



Plate 3 (fig. 3); Figures 27, 28; Map 10 



Alar expanse 29 mm. 



Antenna brownish. Head whitish, second segment of labial palpus 

 brown on outer side, whitish on inner side, apical segment w^hitish. 

 Legs w^hitish, shaded with brown. Thorax and tegula whitish ochreous. 

 Forewing whitish varyingly overcast with brownish ochreous; costa, 

 apex termen narrowly deep ochreous; spot in fold small, purplish; 

 spot at end of cell purplish with scattered whitish scales; faint, out- 

 wardly curving, transverse line from costa at apical third to near 

 tornus; a few fuscous scales scattered irregularly over entire wing; 

 cilia brownish basally, whitish beyond. Hindwing whitish, overcast 

 with gray scales in anal area; cilia whitish becoming darker near wing 

 apex. 



Male genitalia (slide WDD 3611, tjrpe): Uncus short, recurved; 

 gnathos short, broad, dorsoventrally flattened; harpe short, regularly 

 tapering to rounded apex; anellar lobes symmetrical, slightly broader 

 apically, with a group of posteriorly directed spines at posterior apex; 

 aedeagus with two laterally directed spines near apex, vesica armed 

 with one large cornutus. 



Female genitalia: Unknown. 



Type: In the collection of the British Museum (Natural History). 



Type-locality: La Oroya, Rio Inambari, 3100 ft., Peru. 



Distribution: Known only from the type-locality. 



Described from the male holotype: "La Oroya, R. Inambari, 

 S. E. Peru, 3100 ft., wet s., Oct. 1904 (G. Ockenden)." 



This species is very similar to the preceding one, mucida, and 

 the distinguishing characteristics are discussed in the remarks con- 

 cerning that species. 



Lethata optima, new species 



Plate 3 (fig. 4); Figures 29, 30; Map 10 



Alar expanse 34 mm. 



Antenna brown. Head brown dorsally, lighter between eyes; 

 second segment of labial palpus brown on outer side, lighter on inner 

 side, apical segment brown. Fore- and midlegs brown, hindlegs 



