1911] Aldrich — North American Species of Hydrophorus 59 



the tip the outline again rises; the outer side of the tibia is also crooked and convex 

 over the excavation, and along almost its whole length has distinct, long hairs; the 

 inner side is provided with a row of short, erect spines, beginning before the middle, 

 interrupted at the excavation, and continuing again in only three or four spines 

 to a point halfway between the latter and the tip, so that there are no spines near 

 the tip at all, but only delicate pale hairs on the inner side, tarsi simple, with 

 brownish rather large pulvilli. Middle femora slender, a little bowed; middle 

 tibiae with a few extra bristles on the inner side near the tip; tarsus a little shorter 

 than the tibia, its first joint bristly on the inner and hind side, the last two joints 

 black, flattened, and with a dense tuft of stout black hairs on the hind side of each; 

 pulvilli and empodium rather large, brownish. Hind legs of ordinary form. Wings 

 slender, but faintly infuscated, a rather distinct spot on the hind crossvein but 

 none beyond, veins black, humeral and the large stem behind it somewhat paler; 

 abdomen moderately shining above, rather long, strongly concave below; under- 

 neath the fourth segment are two flaps with yellow hair; terminal organs large, 

 folded under. 



Length, 3.9 mm.; of wing 4.8. 



Female. Instead of the long bristles on under side of front femur, there are 

 only a row of short, stiff ones; the front tibia is provided with a simple row of small 

 slanting spines on the inner side, not interrupted and extending to the tip. 



Length, 4.3 mm.; of wing, 4.9. 



Four males and four females: three males and three females 

 were collected at Friday Harbor, Wash., July 17, 1905; two 

 males and two females, same locality, collected by Professor 

 Melander on July 7, 1909; one female. Kanaka Bay, San Juan 

 Island, Wash., (four miles from Friday Harbor) May 31, 1906; 

 and one male sent me many years ago by Mr. Coquillett, Ala- 

 meda, Cal., which is presumably just about the type locality. 



Hydrophorus sodalis Wheeler. 



Male. Occiput green, moderately shining, with only the usual two postverticals; 

 front rather obscure green; face wide, shining green close to the antennae, but with 

 a white pollen covering the lower two-thirds; palpi brown; postorbitals scarcely 

 coming down to the level of the middle of the eye — just ten on a side in the de- 

 scribed specimen, — beard dense and white, no black spines under the neck; cheek 

 forming a narrow vertical plate, densely white poUinose; antennae small, first 

 joint short. Thorax and scutellum greenish bronze, rather shining; acrostichals 

 in a row of five, dorsocentrals sixin each row, the fifth longest, but all rather long, 

 scutellar four, strong; pleurae with dense white dust, especially below; propleura 

 with long white hairs and one black bristle, no other hairs on pleura except a few 

 microscopic white ones on the upper hind part of sternopleura; halteres dark 

 yellow; wings almost pure hyaline, unspotted, third and fourth veins rather widely 

 separated at tip. Color of veins black, scarcely lighter at base. Front coxae with 

 short white hairs, usually a few minute black setules at apex, and occasionally a 



