DICRANOMYIA. 75 



Thorax strikingly gibbous, rising abruptly over the head ; it is 

 brown, almost opaque above, without distinct stripes ; more 

 tawny on the sides and posteriorly ; halteres infuscated ; feet 

 brownish ; coxae and base of the femora pale ; abdomen, including 

 the jnale genitals, fuscous ; ovipositor rather short ; upper valves 

 distinctly curved. Wings comparatively shorter and broader 

 than in the related species, with a slight brownish tinge ; no per- 

 ceptible vestige of a stigma. The first longitudinal vein, instead 

 of ending in the costa, is curved at its tip towards the second 

 longitudinal vein and ends in it ; thus the cross-vein is apparently 

 placed between the first longitudinal vein and the costa ; the tip 

 of the auxiliary vein, with the subcostal cross-vein close by it, is 

 nearly opposite the middle of the praefurca; the submarginal 

 cell is not quite one-third longer than the first posterior ; first 

 and second basal cells of equal length. 



I possess two specimens, a male from the White Mountains 

 and a female from Washington, D. C. 



This species will be very easily recognized by its gibbous 

 thorax and the total absence of a stigma. One of my specimens 

 has the discal cell closed, the other open ; thus I am in doubts, 

 what is the rule and what the exception. 



IS. D. rara, n. sp. 9 • — Brunnea, capite antennisque nigris ; alis apud 

 costani maculis tribus fuscis, quarta ad apicem minore ; vena auxiliari 

 pone prsefurcse initium longe extensa. 



Brown, head and antennae black ; wings with three brown spots near the 

 costa ; a fourth, smaller spot near the apex of the wing ; auxiliary vein 

 prolonged far beyond the origin of the prsefurca. Long. corp. 0.23. 



Head, including the rostrum and the palpi, black ; antennae 

 black. Thorax pale brownish, with three darker stripes above ; 

 a conspicuous dark brown stripe runs from the collare across the 

 pleurae towards the metathorax ; brown spots on the sternum, 

 between the fore and the intermediate coxae ; halteres infuscated ; 

 abdomen brown, segments paler at the basis ; ovipositor sub- 

 ferruginous ; coxae and femora pale tawny ; the latter with a 

 brown band before the tip ; knees pale ; tibiae and tarsi brownish. 

 Wings distinctly infuscated ; a brown spot (sometimes preceded 

 by a pale streak) at the origin of the second vein ; a smaller one 

 at the tip of the auxiliary vein ; a rounded brown spot, included 

 between two whitish ones, at the tip of the first longitudinal 



