236 PROCEEDINGS OP THE ACADEMY OF 



Head yellow, palpi infuscated, antennae yellow, infuscated at tip, front cinere- 

 ous. Thorax yellowish ferruginous, shining ; a narrow brown line in the mid- 

 dle of the praescutum ; halteres yellow, knob infuscated ; feet ferruginous 

 yellow, tips of tarsi brown. Abdomen yellow. Wings yellowish, infuscated at 

 the tip (especially between the stigma and the subapical areolet) ; origin of the 

 petiole and central cross-veins slightly clouded ; subcostal and mediastinal 

 arete tinged with yellow ; stigma oblong, fuscous ; the costal, subcostal, medi- 

 astinal, praescutum and pobrachial veins yellow ; the veins and cross-veins on 

 the apical portion of the wing brown ; the stigraatical cross-vein is near the tip 

 of the subcostal vein, at some distance beyond the origin of the radial fork ; 

 cubital area considerably longer than the second radial one and a little longer 

 than the subapical. 



Three tf and two speoimens. Trenton Falls and Northern Illinois, (nob.) 

 Upper Wisconsin River, (Mr. Ulke), Maine, (Mr. Packard). The specimen from 

 Maine, although undoubtedly belonging to the same species, is distinguished 

 by a darker coloring of the wing ; the veins are brown ; the fuscous tinge at 

 the tip is more intense and extends much farther along the posterior margin ; 

 the pobrachial vein is infuscated ; the nebulae at the central cross-veins and at 

 the origin of the petiole are darker. In some specimens the stigma as well as 

 the infuscated tip of the wing are very pale brown. 



L. luteipennis. Antennis fuscis, thorace cinereo, linea media fusca ; 

 pleuris canescentibus ; abdomine pallide fusco ; alis infuscatis, venis transversis 

 nebulosis ; long. lin. 3 3%. 



Front and vertex cinereous ; proboscis and palpi brown ; antennae brown ; 

 upper side of first joint cinereous ; base of third pale. Praescutum brownish 

 cinereous ; intermediate stripe double, but more or less obsolete ; a longitudinal 

 brown line in its middle always distinct; indications of the lateral stripes near 

 the suture and on the scutum; the latter and metathorax brownish cinereous ; 

 scutellum reddish, with a brown line in the middle ; pleurae bluish hoary ; 

 halteres pale, with dusky knob ; feet tawny ; tip of femora and of tibiae and 

 tarsi more or less infuscated. Tergum tawny ; venter paler ; male forceps 

 having one of the falciform appendages ciliated. (Fig. 24.) Wings infuscated; 

 all cross-veins, origin of petiole, base of petiolated areolet and tips of anal and 

 axillary veins, clouded ; subcostal vein ferruginous ; other veins dark brown. 

 Cubital area a little longer than the subapical. The proportion between the 

 length of the petiolated areolet and its petiole is not constant; generally, the 

 areolet is a little longer, although sometimes it is shorter than the petiole. In 

 one of my specimens the areolet is more, than twice shorter than its petiole on 

 one wing, and it is altogether wanting in the other. A stump of a vein near 

 the origin of the petiole. 



Common at Washington from the earliest Spring through the greatest part 

 of the Summer. I observed them swarming and copulating on the 19th of 

 April, 1859, just before sunset, and caught them also in July. Florida, (in 

 March, 1858.) Massachusetts, (Mr. Scudder.) 



Compared eight ^ and seven 9 specimens. 



L. toxoneura. Fusco silacea, antennis fuscis ; alis subhyalinis, stigmate 

 pallido; vena radiali (ante furcam), conspicue arcuata ; long. lin. 3 3. 



Front cinereous ; palpi infuscated ; proboscis yellow ; antennae brown ; base 

 of third joint pale. Thorax brownish yellow, with two pale brown stripes, 

 which are very distinct on, and before, the scutum, and paler near the collare, 

 where they communicate with a brown spot near the humerus ; pleurae pale, 

 sometimes with a pale brown stripe ; halteres pale, slightly infuscated ; feet 

 pale tawny, tips slightly infuscated. Abdomen tawny, lateral margins brown. 

 Wings pale cinereous ; stigma pale ; the petiole forms a line nearly straight with 

 the cubital vein, (and not with the radial vein, as is frequently the case in other 

 species); the portion of the cubital vein anterior to the central cross-vein is 



[Aug. 



