148 PROCEEDINGS OF THE NATIONAL MUSEUM. voi,.xxi. 



In the latter there is a distinct luteous shading, especially well marked 

 in the secondaries, of which there is no trace in the former. 



Sperata, emacidato, distans, impressa, and noctivaga have short, stumpy, 

 trigonate primaries. All of them have a distinct, round orbicular, a 

 very large, smudgy reniform, all the transverse lines distinct, and a more 

 or less obvious median shade line. 



Sperata, which is of a very pale ash gray, has no other markings, and 

 even what there is does not contrast. It is an inconspicuous, powdery 

 form, and recognizable thereby. 



Emaculata is quite as powdery, but very much darker, so the black 

 lines do not distinctly contrast. It has added a black, shaded streak 

 at base, a black claviform, and a dusky shade near the anal angle. 



Distans is much paler gray in ground color, hence the black lines and 

 markings contrast more decidedly. The markings are as in the i)re- 

 vious species, but the shadings below tlie submedian vein are more 

 diffuse and prominent, and usually darken the wing from base to anal 

 angle. There is often a break, however, between the claviform and the 

 transverse posterior line in this dusky shade. As a whole tlie prima- 

 ries arc narrower and more pointed, and on analysis the resemblance 

 to alni becomes strongly evident. 



Impressa is broader winged and has the apices of primaries less 

 marked. It is a clearer gray form, with all the markings distinctly 

 written, and there is no continuous dark shading through the lower 

 half of primaries. In the female the transverse anterior line is always 

 distinct, while in distans it is almost always broken and obscured. Dis- 

 tans and impressa are very closely allied, and I would scarcely have 

 cared to separate them on imaginal characters had not l)r. Dyar noted 

 a difference in the larvae, which gave additional value to the i)oints 

 above noted. With extremes at hand, no difficulties can arise, nor if 

 there is a good series of each form for comparison ; but with a small 

 number of variable specimens it may not be easy to decide as to the 

 species. 



Noctivaga is sharply defined by its mottled black and white appear- 

 ance. The ground color is white, or nearly so, and all the lines, spots, 

 shades, and dashes are black and diffuse. The secondaries are dark 

 smoky, and altogether this form is hardly to be mistaken. 



All the other species are more or less strigate in their type of macula- 

 tion, and this is particularly t!ue of barnesii, perdita, and edoJata, in 

 which the primaries appear blackish. Barnesii and perdita have the 

 primaries evidently trigonate, though with a long, evenly curved outer 

 margin and acute apex. Barnesii is paler in ground color, but all the 

 transverse maculatiou has disappeared, while of the ordinary spots the 

 reniform is sometimes traceable as a smoky lunule. The wing as a 

 whole seems darker interiorly, owing to a prominent black shade, which 

 extends through the submedian interspace from base to anal angle. 



Perdita has the primaries more uniformly blackish, but both the 



