206 BLACK ARCHES. 



more slender than in the preceding genera, the 

 male having the apex of the abdomen slightly 

 tufted, while that of the female is naked and atte- 

 nuated*. Psilura is very closely related to Hypo- 

 gymna, a genus including the Gipsey Moth, whose 

 curious economy renders it an object of much 

 interest. The principal differences consist in the 

 relative length of the articulations of the palpi and 

 the appearance of the abdomen in the respective 

 females, that of the Gipsey Moth terminating in a 

 dense tuft of hairs. 



The male of the Black Arches Moth generally 

 expands from fifteen to eighteen lines, the female 

 about two inches. Both sexes vary considerably, 

 but the following description will apply to the ma- 

 jority of specimens. The surface of the primary 

 wings is greyish- white, with numerous black spots, 

 and four confused zigzag transverse lines of the 

 same colour. Several of the spots are placed at the 

 base of the wing, one before the middle between 

 the two anterior lines, and a regular series along 

 the terminal border. The secondary wings are 

 brownish-grey, sometimes white at the hinder extre- 

 mity; the fringe always white, spotted at regular 

 intervals with black. The thorax is white, tinged 

 with yellow in front, and marked with several 

 black spots; the abdomen rose-red behind, with 

 the incisures and series of spots black, that of the 

 female terminating in a yellow corneous oviduct. 



* The generic name refers to this circumstance, being 

 derived from $i).ot naked, and ovga, the tail. 



