16 PROCEEDINGS OF THE NATIONAL MUSEUM. vnr. 81. 



The first joint narrowly blackish on the upper edge, the third mostly 

 brown. 



Mesonotum shining green with a coppery stripe on each side along 

 the suture. Scutellum shining green. Pleurae blackish green, cov- 

 ered with a thin gray dust. Cilia of the calypters black. Halteres 

 yellow. Abdomen shining green, but less bright than the thorax. 

 I'osteriorly it is compressed. Hypopygium large, blackish green. 

 Lamellae nearly circular, white with a very narrow dark border. 

 The front edge deeply incised from half a dozen long processes with 

 bristles at the tip. 



Legs yellow. The middle and hind coxae blackish except at tip. 

 The hind tibiae blackened from about the middle to end. Tarsi 

 entirely black. Front and middle tarsi gradually infuscated toward 

 the apex. Front coxae with black hairs on the anterior surface. 



Wings hyaline, rather narrow in shape, the anal angle not very 

 prominent. The fourth longitudinal vein sharply bent beyond the 

 cross vein with a stump of a vein at one or both of the bends. Costa 

 with an elongated swelling not very large at the junction of the first 

 vein. 



Female. — Face about half wider than in the male. Hind tibiae in- 

 fuscated on the apical fourth, otherwise about as in the male. 



Length 4 mm. 



Described from G males and 5 females collected at Tantalus and 

 Waialua, Oahu, and at Olaa, Hawaii, 2,500 feet (0.76 kilometer), all 

 in the Hawaiian Islands, by W. H. Ashmead. 



Type.—M^\Q, Cat. No. 25197, U.S.N.M., from Tantalus. 



This is the only true DoUchopus known to me to occur in a tropi- 

 cal climate. The species is not known from North America ; it would 

 run to abrasus on page 20 in the tables of Bulletin 116, but is readily 

 separable by its short, broad lamellae. It may have been introduced 

 from Japan, but tlie species of that region are too imperfectly 

 knoAvn as yet to settle that point. 



Genus HYDROPHORUS Fallen. 



Jlydroplionis Fallen, Diptera Sueciae, Dolichopotles, 1823, p. 2. — Loew, 



Smiths. Misc. Colls., No. 171, 1864, p. 211.— Aijjkich, Psyche, vol. 18, 



pp. 45-73, 1 pi., 1911. 



Six species of this genus were collected in Alaska in my expedition 



of June and July, 1921 ; one was undescribed, none European, and 



all but two occur in the United States. 



HYDROPHORUS ALTIVAGUS Aldrich. 



Hydrophorus oliivutjVH Aldrich, Psyche, vol. 18, p. 67. 1911. 

 Ten specimens, Anchorage and Fairbanks, Alaska. Described from 

 Colorado, and I afterwards collected it at Moscow, Idaho. 



