20-1: PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxv 



reaching- to and sometimes exceediiii:^ middle of front, rather slender, 

 the terminal joint proportionately ratluM- loni^-, obliijue or even droop- 

 ing, vestitur^ loose. Antennse in the male feebly ciliated. Thorax 

 moderately dev^eloped, with loose, long, thin vestiture forming no 

 tufts and leaving collar and patagia? undefined. Abdomen reaching to 

 or exceeding the hind angle of secondaries, more often longer and 

 somewhat disproportionately slight. Legs unarmed except for the 

 usual tibial spurs, in the male with more or less well-marked sexual 

 tuftings, which aie most obvious on the middle tibiae Primaries 

 rather narrow, elongate, the costa a little depressed, apices a little 

 pointed, outer margin a little arcuate or entirely rigid, oblique. 



The male genitalia are of the same type in all, and very nuich alike: 

 there is a pair of oblong harpes, roiuided at the tip, broadly or nar 

 rowly as the case may be, not modified or spined in any way, and on 

 each a single curved corneous clasper. varying somewhat in the species. 



The genus ditiers from Lcucaula chietiy in the narrow subequal 

 primaries, having the costa depressed, the outer luargin rather rigidly 

 cut off', and in the long abdomen. The loose, hairy vestiture, forming 

 no tufts and leaving the thoracic parts imdetined, adds to the distinctive 

 appearance. 



As a whole the species resemble each other closely. The primaries 

 range from pale creamy yellow to reddish, the costal edge white in 

 the species known to me, tuedian vein usually white and usually a 

 dusky longitudinal shade through the middle. 



Nlve'icosta is the best marked and a little the luore robust of the 

 species, the body parts being stouter in proportion than in any of the 

 others. The primaries are reddish luteous, the costa narrowly yet 

 distinctly white. The median vein is also white, though not promi- 

 nently so, and it is usually accompanied b}" a well-marked dusky shad- 

 ing which may reach ver}' close to the outer margin. The transverse 

 posterior line is punctiform and completely traceable in all the speci- 

 mens. The secondaries are slightly smoky, with a faint reddish or 

 3^ellowish tinge. The male has a fringing of thin hair on the under 

 side of the anterior and posterior femora, and on the middle femur 

 there is an expansile tuft of hair at the l^ase. The anterior and poste- 

 rior til)iie ai"e hairy, but not really tufted; the middle tibia has a dense 

 brush or tuft of hair extending all the wa}^ down the outer side, and 

 this is capable of fan-like expansion. All the specimens are from 

 Colorado. 



Bicohnuiia has the primaries a very pale yellow and the secondaries 

 reddish, in some specimens the wings are i)ractically inunaculate, 

 and of this form was the type of the species. In most good examples, 

 however, the white costa and median vein are obvious, and in one 

 specimen the punctiform transverse posterior line is almost complete 

 The body is smaller and the a})domen in ))oth sexes is much longer 

 than in the preceding species. 



