BOA RMTD.-E—BISTON. 1 19 



We have three species ; easily recognised : 



A. Fore wings thinly scaled, yellowish-grey, striped with 



black. B. hirtarius 



A^. Fore wings white with black speckling and two pale 



chocolate bands. B. prodromao^us. 



A:\ All the wings white, dusted with black, or else wholly 



smoky-black. B. hdulnrius. 



1. B. hirtarius, Z. — Expanse 1| to 2 inches. Antennte 

 strongly pectinated ; head and thorax hairy, the latter very 

 stout and fluffy; fore wings thickly ribbed, thinly scaled, 

 yellowish-grey, dusted with black, and having black trans- 

 verse narrow stripes ; hind wings thinly scaled, pale grey. 



Antenna of the male broadly pectinated with long, slender 

 ciliated teeth which cease before the apex, leaving it merely 

 notched, black-brown ; palpi hidden by masses of hairy scales ; 

 head rough from similar erect scales, dull brown ; thorax 

 broad and very thick, covered by a great mass of upstanding 

 scales, yellow-brown, transversely barred with black on the 

 collar, the middle, and the hinder portion, where the long 

 scales form two small crest-like knobs ; abdomen short, 

 moderately stout, but tapering, reddish-brown, rough with 

 long scales which form one or two prostrate dorsal tufts, 

 blacker than the rest ; anal tuft thin and rather ragged. 

 Fore wings elongated, costa very faintly hollowed to beyond 

 the middle, thence slightly rounded ; apex squarely angulated; 

 hind margin beneath it rather full, but sweeping oS" obliquely 

 in a long curve ; dorsal margin nearly straight ; colour 

 yellowish-grey finely dusted with black ; first line curved, 

 black, spread upon the nervures ; second line deep black, 

 gracefully curved outward and back to the costa ; between 

 these two, but nearer the latter, is an irregular black central 

 stripe, and outside the second line, in contact with it, a more 

 or less distinct grey-black band, blackened on all the nervures, 

 and followed by a narrow pale stripe of greyish-yellow ; out- 

 side this the bind-marginal region is a little clouded with 



