AMERTCAN LEPIDOPTERA. 315 



they faithful representations, they would indicate a passing of the one 

 style of coloration into the other, which intermediate grades have nev- 

 er come under our observation. 



In addition to the black wings of umhrosa, there are the marked 

 differences of color as compared with the species from which we sepa- 

 rate it, of the duller shade of the anteriors as above described, and a 

 less degree of blackness of the spots. There is also a translucency of 

 the wings, which usually permits the silver character of the under sur- 

 face to be seen from above. This translucency is very noticeable when 

 the insect is held between the eye and the light, when, also, tlie obso- 

 leteness of the spots of the inferiors is favorably shown, in the almost 

 immaculate appearance of the wings. 



But if these differences are of questionable specific importance, con- 

 clusive evidence of the distinctness of our two species is afforded in the 

 shape of the wings, viz., in the curve of the costo-apical margin of the 

 primaries, in the degree of excavation of their posterior and interior 

 margins and in the length of the tails. Placed side by side, these feat- 

 ures will at once strike the eye, and so marked and constant are they, 

 that from comparison of outline alone, the species can be determined. 

 There is also a difference in their sizes, — the expanse of interrogdtionix 

 being in the S 2.50, 9 2.75 inches, which exceeds wm/y/'osa by .25 inch. 



Additional confirmation of the validity of this species, may be found 

 in the circumstances under which it first was brought to my observation. 

 During the first week of July 1861, there were brought to me at Scho- 

 harie, fourteen larvie and chrysalides taken from or very near a garden 

 hop-vine, which, from the casual notice given them, were presumed to 

 be those of Inter rogationis. The larvfe were mature, and in a day or 

 two entered their pupal state. The imagines emerging in about twelve 

 days, proved, to my surprise, to be every one of the "black variety" — 

 three males and eleven females. About the middle of July, several 

 otlier seemingly identical larvae were taken by me from hop-vines, 

 which emerging the last of the month, gave the ordinary interrogationis. 

 Impressed with a belief in the specific difference of the "black variety" 

 I endeavored to ascertain its larva, and to this end, collected on Aug. 

 10th two chrysalides, and twenty larvse varying from one half-inch in 

 length to nearly full size. During the ensuing two weeks many addi- 

 tional larvae were taken by me from hop. yards, and grouped in four 

 breeding cages, in accordance with colorational differences which were 

 observed and noted. Of these differences, in lieu of copying at length 

 the notes then taken, it may sufiice at the present to state that they 



