HYDRELLINA. 153 



little grayish; the second segment of the costal vein scarcely half 

 as long again as the third. Not possessing any of the few Eu- 

 ropean Hydrellice with dark colored faces, I cannot point out bow 

 H. obscuriceps differs from them. 



Hob. Middle States. (Osten-Sacken.) 



4. II. scapularis LOEW. 9 Subsenescenti-fusca, antennis nigris, 

 facie ochracea, puncto frontal! pallidius flavo, interdum albido, thoracis 

 margine antico, humeris pleurisque albo-pollinosis, pedibus nigris, me- 

 tatarsis posticis rufis. 



Brassy-brown ; antennae black, face ochraceous, frontal dot paler yellow, 

 sometimes whitish, anterior border of the thorax, shoulders, and pleurse 

 dusted with white; legs black, first joint of the hind tarsi red. Long, 

 corp. 0.1. Long. al. 0.12. 



Very similar to H. hypoleuca, notwithstanding the different color 

 of its face, but certainly not a variation in color of that species. 

 Face a little narrower above than in the latter, quite as broad 

 underneath, thus appearing more dilated below, likewise keeled on 

 its whole length, but more distinctly and a little less obtusely; on 

 each side of it there are three small bristles; its color is dark 

 ochraceous. Antennae black ; bristle with five or six rays. Front 

 dusted with brown, opaque, narrower than in H. hypoleuca; the 

 dot immediately above the antennce is dusted with paler yellow or 

 whitish. Thorax dusted with brown, opaque, the dust not being 

 so thick as to prevent its color from inclining a little to greenish; 

 its outermost anterior border and the shoulders are dusted with 

 whitish ; the dust of the pleura? is of the same color. Upper side 

 of the abdomen greener than that of the thorax, slightly dusted, 

 but also slightly glossy ; its under side and the part of the upper 

 abdominal plates which is turned downward, are but thinly dusted 

 with whitish. Legs black; first joint of the posterior tarsi yellow- 

 ish-red ; first joint of the anterior tarsi brown at the base. Poisers 

 yellow. Wings glassy, rather grayish; the second segment of the 

 costal vein more than half as long again as the third. 



Hob. United States. (Schaum.) 



5. H. valida LOEW. . Inter majores sui generis; glauco-cinerea, 

 tota opaca, facie latiuscula pallide ochracea, anteunis pedibusqiie nigris, 

 basi tarsorum omnium rufa. 



Belonging to the largest species of this genus ; greenish-gray, opaque every- 



