ANTHKAX. 135 



is concealed under these scales, and becomes visible after their removal only ; the shade 

 of colour of the scales is sometimes different in the two sexes. In the same group of 

 species the cross-bands of a yellow tomentum sometimes existing at the base of segments 

 2-4 are more conspicuous in the female ; in the male they are hidden under longer hairs 

 of the same colour, these hairs being more dense in this sex. 



Species of Hyalanthrax occur both in Europe and in North America, and those of 

 one continent show remarkable analogies to those of the other. They are difficult to 

 discriminate, and still more difficult to describe ; even the European species are not suf- 

 ficiently worked out. The group distinguished by its smooth front tibiae (A. faustina, 

 A. sabina, A. lateralis, Say, &c.) seems to be peculiar to America. 



I need hardly repeat here that the presence of hyaline wings alone is not sufficient 

 to characterize a Hyalanthrax. I have before me an undescribed species from Texas 

 with hyaline wings and a dense covering of golden fulvous hair ; this species, however, 

 is abundantly distinguished from Hyalanthrax by the long, conical, third antennal joint, 

 the conically projecting face, the front tarsi without the characteristic delicate pubes- 

 cence of erect hairs, the different shape of the whole body, &c. 



Synopsis of the Species of the Subgenus Hyalanthrax described below. 



Sides of the abdomen with tufts of black hair on segments 3, 5, 

 and 6. 

 Front tibise smooth, without any spinules ; abdomen with narrow 

 cross-bands of a scaly tomentum on all the segments. 

 Second abdominal segment with a white cross-band. 



Knob of the halteres infuscated ; abdomen of the male 



with silvery scales at the end 27. faustina, sp. n. 



Knob of the halteres yellow ; abdomen of the male 



without silvery scales at the end 28. sabina, sp.n. 



Second abdominal segment with a yellow cross-band like 



that of the other segments 29. sp. ? 



Front tibise beset with spinules. 



Abdomen without distinct cross-bands ; the enlargement at 

 the base of the costa in the male clothed with 

 silvery scales ; general colour of the pubescence 



greyish 30. moneta, sp. n. 



Abdomen with conspicuous cross-bands of yellowish- white 

 scaly hairs ; the tufts of black hair on the sides of 



the abdomen large and conspicuous 31. stenozona, Loew (?). 



Sides of the abdomen with tufts of black hair on segments 5 and 6 

 only. 

 The fringe of hair on the sides of the abdomen short and but 



little conspicuous 32. livia, sp. n. 



The fringe of hair on the sides of the abdomen rather long and 

 conspicuous; patagia of the male clothed with bright 

 silvery, those of the female with more yellowish, scales . 33. agrippina, sp. n. 



