1911] Aldrich — North American Species of Hydrophorus 51 



suture, where a cluster of whitish hairs occurs in some species (gratiosus), pro- 

 pleura with long white hairs and a bunch of black bristles above the coxa; meta- 

 pleura also with white hairs; scutellum with a row of erect convergent bristles on 

 the margin on each side, five or six in each; some supernumerary bristles also before 

 the scutellum; halteres yellow. Front coxae with white hair, long above and 

 shorter below, and a row of small black bristles just above the trochanter; middle 

 and hind coxae with only fine white hair; front femur with irregularly placed 

 spines of all sizes below, indistinctly arranged in a double inner and a single outer 

 row; front tibia stout, gently curved, ending in a slight process with one con- 

 spicuous spine, the rest of the inner spines almost imperceptible; the other legs 

 and all the feet somewhat bristly; pul villi brownish; the legs in every part showing 

 the characteristic plumbeous pruinosity of the species. Wings rather opaque 

 whitish, with a fa"int brown cloud occupying all the apical two-fifths except a 

 whitish spot in the first posterior cell, and another spot of deeper brown with its 

 center in the basal part of the discal cell and diffusing into the surrounding cells; 

 veins black. 



Length, 5.6 mm.; of wing, .5.7. 



A single female, Grand Coulee, Wash., Soap Lake, June 29, 

 1902, from the collection of the Washington State College 

 through Professor Melander. 



This species has so many well-marked characters that it is 

 unnecessary to enumerate them. It was collected at a small 

 lake of strongly alkaline water. 



Hydrophorus intentus sp. nov. (fig. 4.) 



Male. Everywhere covered with a dense pruinosity, yellowish except on the 

 dorsum of the thorax, and front where it is brown; metaUic ground color not 

 visible except very slightly on the abdomen. Occiput with a row of spines extend- 

 ing each way from the postverticals and joining the orbitals rather far down the 

 side; the orbitals extend down nearly to the lower border of the eye; behind them 

 the usual beard is yellowish, and there are black spines under the neck; front seal- 

 brown, face uniformly yellowish pollinose throughout, palpi concolorous in favor- 

 able light; antennae wholly black, first joint moderately long and slender, third 

 wide. Dorsum of thorax rather uniformly brown, humeri lighter; humeral bristles 

 two or three, scutellar about three pairs which are convergent and rather erect, 

 the outer sometimes considerably smaller; propleura with long yellowish hairs 

 and one black bristle; metaplem-a with fine soft yellow hairs and a few still smaller 

 behind the humerus, above the notopleural suture; halteres yellow. Hairs of the 

 coxae all pale yellow, long on front ones, which have some black spines on the hind 

 side, next the body, hard to see. Fore femur with two rows of spines underneath, 

 the outer of about seven quite uniform, the inner with four or five larger and an 

 irregular intermixture of smaller ones; front tibia almost straight, with a row of 

 small spines on inner side, the last one larger and erect, standing on a slight elevation; 

 pulvilli brownish. Wings somewhat uniformly brownish, the veins almost black, 

 not lighter at base, an almost imperceptible cloud on the hind crossvein and another 



