890 CHARLES PAauL ALEXANDER 
2. Vein R: obliterated by atrophy (this is also the case to a lesser extent in Tipula sub- 
fasciata and T. penobscot), or else (as in Brachypremna) the second anal vein very 
short, not more than one-third the length of the first anal vein; legs very slender, 
filiform. A hota an pee Abeer cr ehh et ses tas Ca ee a Dolichopezini (p. 928) 
Vein R2 present for its entire length (except in Tipula sudfasciata, T. penobscot, and 
other species); second anal vein longer, one-half the length of first anal vein; legs 
stouter and usually shorter than in Dolichopezini.............................00. 3 
3. Antennae without verticils (see Stygeropis, below); flagella of the male antennae 
DOCU ALE Hs Ak ie ee RNs Mints Ale Dy UIs SARL OR Ctenophorini (p. 930) 
Antennae verticillate (except in Stygeropis and most species of Holorusia); flagella 
of the male antennae not pectinate (in some species of Nephrotoma and Tipula the 
ventral face of the segments is often deeply incised, producing a serrate appearance, 
but the antennae in the northern forms are never pectinate).......... Tipulini (p. 932) 
4. Four branches of radius reaching the margin (see note on Gonomyia blanda, below).....5 
Two or three branches of radius reaching the margin....................2.20-0005- 9 
5) Dibiae*spurredjat tips. 65 4.) eee ee Sica ek A es ES eee eee 6 
Tibiae without spurs at tip. (Gonomyia blanda, p. 905, has R:z in close proximity to 
R, at the wing margin, so that but three branches of the radius appear to reach the 
wing margin; the tropical antochine genus Paratropeza will also run to here, and has 
been mistaken by some authors for a Gnophomyia; the investigator must always 
be on the lookout for such aberrant genera and species, especially when dealing with 
tropicalomiaterials) i seyret esis ese ees tac ata Steere Eriopterini (p. 901) 
6. Antennae with from 6 to 10 segments.................-2-.00000-5 Hexatomini (p. ot) 
Antennae with more than 10\segments..........0...205 4. ses oe ee Ie eee 
7. Sce beyond the origin of Rs.................- Limnophilini (p. 913) (except genus te 
Sez before the origin of Rss cl shes vees bo oe oie soe Oe eee eee 
8. Antennae 17-segmented; wings pubescent....... Genus Ula, tribe Limnophilini (p. 013) 
Antennae 13- to 16-segmented; wings glabrous..................... Pediciini (p. 923) 
9. Tibiae spurred; an apparent fusion of Rit+2+s to the wing margin so that but two 
branches of the radius are present (except in Phalacrocera neorena, in which three 
branches are present). The European hexatomine genus Cladolipes runs to here but 
has only eight antennal segments; the South American species Psaronius abnormis 
also comes here, but may be readily separated by the very elongate subcosta. 
Subfamily Cylindrotominae (p. ey, 
Tibiae without spurs; no contiguity of R: and R243; at their tips.................... 
10. Antennae 12-, 15-, or 16-segmented; claws usually without teeth on their lower side.. i 
Antennae 14- segmented: claws with teeth on their lower side....... Limnobiini (p. 890) 
11. Cross-vein r lacking; Sc ending before the origin of the short Rs; R2+3; upcurved at 
the end, R:15 bent strongly toward the apex of the wing producing a trumpet-shaped 
cell Rs; cell 1st M2, when present, pointed at the inner end. 
Subgenus Leiponeura, genus Gonomyia, tribe Eriopterini (p. 905) 
Cross-vein r present or lacking; if lacking, Sc ends far beyond the origin of Rs; Ro+3 not 
strongly upcurved at end, and R.+; not bent strongly toward the apex of the wing; 
inner end of cell /st M2 not pointed..........................00. Antochini (p. 897) 
The nearly wingless snow fly, Chionea, belongs to the tribe Eriopterini 
(page 902). 
SUBFAMILY Limnobiinae 
Tribe Limnobiini 
The genera of the tribe Limnobiini may be separated by the following key : 
1. Rostrum elongated, longer than head and thorax together couriers Geranomyia Hal. (p. sou | 
» Rostrum not elongated, shorter than the head): . 755.0 c 010. = ciicerelsteveielsteteteieieisieiel oilers 
