^><'-'>^J DirTERA OF rOXXKCTrClT: TAXONOMY 415 



phological characters lie in the reduction in nunil)er of anteinial se«^- 

 luents, correlated with a tremendous elon<^ation in this or«,'an in the 

 males of several species, and the presence of a strong protuberance or 

 tubercle on the vertex. As regards venation, the reduction in num- 

 ber of branches of Media is very striking (Fig. -14. J-N), there being 

 species with all four branches, including cell 71/, ))resent ; many others 

 with only three l)ranches. and cell M\ lost by fusion of adjacent veins; 

 Avhile in the subgenus Eexatovm^ cell Ut M-2 is open by the entire 

 atr(>i)hy of m. and both sections of vein J/;., there being but two bran- 

 ches of the vein attaining the wing margin. In the chiefly Palaearctic 

 subgenus Cladollpes Loew, the radial held is similarly reduced, cell R-.^ 

 being lost by the fusion of enclosing veins, a condition that is presaged 

 by the local He.vatoma {He:i'ato))ia) megacera. The species of the sub- 

 genus Hexafoma and some closely allied Enocera have the valves of 

 the ovipositor short and only feebly sclerotized. while tlie other and 

 more numerous species have these valves unusually long and acutely 

 pointed. 



The adult tiies of certain species of Krhcera are among the most 

 rapid-flying and active of all known Tipulidae, sometimes appearing 

 in vast swarms near the banks of major streams and rivers. Their 

 larvae live in Avater or saturated soil and are intensely carnivorous. 

 When ready to pupate, they come to sandy soil at the bank of the 

 stream. The larvae of Hexatoma {Eriocerd) alb/' f arsis ((). S.) and 

 H. {E.) hrevloncornis Alex., formerly held to belong to a separate 

 subgeneric group, Penthoptera, frecpient rich organic mud in wooded 

 swamps or along densely shaded streams. 



Hexatoma Latrcillc 



isoi). Hexatoma Latreille; Gen. Crust, et Ins.. 4:260. 

 Isls. Anisomera ^Nleigen; Syst. Beschr. Zweifl. Ins., 1:210. 



A';'_v to Subgenera 



1. Wilms with cell 1st j\U open; two branches of M reach the mar-iin (iMg. 



_j^' T j^\ Hexatoma 



Wings with cell Isf M- closed; tliree or four brandies of M reach the mar- 

 gin (Fig. 44, L, M, N) : ■ Enocera 



Subgenus Hexatoma Latreille 



The .subgenus Hexafoma, in our fauna, includes but tAvo species, 

 one of which may prove not to be regional. The extreme reduction of 

 the medial held is parallelled only by a subgenus of Limonia Meigen 

 {Alexandria)^ Garrett). The antennae are reduced to but six evi- 

 dent segments, Avith an additional minute "button", in the male, and 

 Avith the sixth segment of the female sometimes vaguely divided by in- 

 complete constrictions. The adult flies rest on vegetation along the 

 banks of large creeks having sandy margins, Avherein may be found 

 the early stages. 



Key to Species 

 1 Cell Rs of wings verv small, subequal to or shorter tiian its petiole (Fig. 44, 



J) ; Rs and its anterior branch without macrotnchia : antennae {$) '^"S. 



approximately one-half longer than the entire body megacera 



