"150 PROCEEDINGS OF THE NATIONAL MUSEUM. 



longer process up. The variation is in the proportion of these parts to 

 each other, the tendency in our species being to the disappearance of 

 the thumb and to the formation of a single, long curved hook similar 

 to that in the first or americana group. 



In the stumpy-winged series sperata is, on tlie whole, the most typ- 

 ical, with the thumb well developed, stout, and pointed at tip; the finger 

 of moderate length, more slender, and easily curved to the pointed tip. 



Emamdata strengthens the thumb and shortens it a little, while the 

 finger is much lengthened, becomes much stouter, and is nearly straight 

 to an abruptly jiointed tip. Distans and impressa intensify this struc- 

 ture, the thumb being perhaps a little longer and the finger a little 

 shorter. 



Noctivaga, on the other hand, loses the thumb almost completely, the 

 finger remaining much as in sperata. 



Of the strongly strigate species, harnesii is like sjyerata, with the 

 thumb greatly strengthened, but the proportions not much changed in 

 other respects. Perdita is similar, but here the finger is also strength- 

 ened, though it becomes shorter. In edolata the thumb is much reduced, 

 forming, indeed, a mere beak or spur, while the finger is very long, 

 slender, and curved. This type is also found in all the other species of 

 the group, the tendency to lose the thumb becoming absolute in oblinita, 

 which then may be confused with the group americana at first sight. 

 Unfortunately, I have had no male of lanceolata. 



Of the European specimens referable to this group, I know anricoma, 

 rumicis, euphorhiae, myrica, and menyanthidis, all belonging in a general 

 way to the stumpy- winged form. 



Euphorhiae in sexual structure is almost identical with fiperata^ and 

 the species resemble each other very closely. 



Myrica bears the same relation to euphorhiae in genital structure that 

 noctivaga does to sperata, and here also the European and American 

 species are very close structurally, while totally different in superficial 

 appearance. Myrica is a very dark, evenly powdered, ashen gray, on 

 which the ordinary markings are easily traceable, though they are not 

 prominent. 



Auricoma and rumicis represent the form found in impressa, our 

 species standing almost midway between the two European forms in 

 structure and resembling both superficially. 



Wc have nothing resembling menyanthidis, in which both finger and 

 thumb are long, slender, and curved, the thumb distinctly longer and 

 a little up curved. Here we have a very distinct tendency to the alni 

 type, which is not much contradicted in superficial appearance if we 

 eliminate the peculiar black shading of the latter There is nothing in 

 the Euroi)ean species known to me which resembles our narrow- winged 

 species. Ahscondita, of which I have only a single specimen, resembles 

 euphorhiae and will probably have similar sexual characters. 



Ligustri has sexual structures totally unlike anything else in the 

 genus and should be excluded from it even ou superficial characters. 



