114 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.49. 



Bigot's species are reduced to synonymy, except latipdlpis, and 

 seven new species are described, five of them in only one sex. In 

 the 20 years from this paper to the present Johnson has described 

 two species, Adams one, and Coquillett one more. 



In the followuig pages 22 species are recognized, of which 11 are 

 known in both sexes, the male only in 5, and the female only in 6. 

 Two or three of them are not firmly established. These figures show 

 how much still remains to be done in collecting and studying the 

 group. 



Generic characters. — The genus includes Leptid flies with five pos- 

 terior cells, the anal cell open; third antcnnal jouit simple, rather 

 deep vertically, attached above its middle, usually kidney-shaped 

 (sometimes concave in profile below the arista, then not quite kidney- 

 shaped); arista subapical; tibial spurs none in front, two in the mid- 

 dle, one behind, but often quite weak in males. 



Specific characters. — There are several characters which may be 

 used singly to divide the genus into two groups of several species 

 each. Five species have the third antennal joint concave in profile 

 below the arista, a character applying equally to both sexes and 

 very distinct; sides of face pilose is found in nine species, but is 

 slight in a few oases, especially in the female; infuscation of the hal- 

 teres seems to be very useful, but there are cases in which it occurs 

 in the male and not m the female. Color characters occur in anten- 

 nae, palpi, legs, and abdomen, but except the last are prone to be 

 variable and can be used only with great caution. Width of the 

 front is a good character in females, several species having it much 

 wider than one eye (always measured just above the antennae, 

 viewed from in front). Several males of the group with concave 

 third joint have a thornlike bunch of spines- on the middle coxa, a 

 very striking thing. Many males have on the front side of the hind 

 coxae near the tip a distinct condyle, smooth, polished, rounded or 

 conical, which fits into a correspondmg socket m the hind side of the 

 middle coxa. I have made but little use of this, because it is nor- 

 mally almost invisible and I could not compare its form satisfactorily 

 in different species. I have not studied the male genitalia, although 

 I do not doubt that in the course of time they will be fomid useful in 

 critical cases. In my opinion it is not safe to dej^end merely on 

 their characters as they occur in ordinary specimens, as they are not 

 always folded in the same manner in the same species. It will prob- 

 ably be necessary to detach the organs and make permanent inounts 

 of them. 



Habits. — The bloodsucking habit of the female in one species is 

 alluded to above in the quotation from Osten Sacken. Kjiab * 



1 Proc. Washington Ent. Soc, vol. 14, 1912, pp. lOS, IIG; and vol. 17, 1915, p. 38. 



