126 DIPTERA OF NORTH AMERICA. j_PART IV. 



nition. The manner in which the first longitudinal vein joins 

 the costa reminds us of Toxorrhina ; otherwise the genus stands 

 isolated, and no immediate relationship can be pointed out. The 

 absence of distinct empodia and the presence of small teeth on 

 the under' side of the ungues constitute a leaning towards the 

 Limnobina, which is balanced, however, by the structure of the 

 forceps, etc. 



Antocha was introduced by me in the Proc. Acad. Nat. Sci. 

 Philad. 1859, p. 219. Since then, the only species {A. opalizans) 

 has been found to occur in Europe also (comp. Schiner, Fauna 

 Austriaca, Diptera, Yol. II, p. 559). 



The name of the genus is derived from its principal character, 

 the proximity of the auxiliary and the first longitudinal veins 

 {avtozn, close approximation, connection). 



Description of the species. 

 1. A. opalizans 0. S. % and £. — Ochracea vel cinerea, thoracis 

 vittis infuscatis ; halteres capitulo fusco ; alse opalizantes, basi pallida. 

 Ochniceous or gray, stripes of the thorax infuscated ; knob of the halteres 



brown ; wings opalescent, pale at the basis. Long. corp. 0.22 — 0.32. 

 Syn. Antocha opalizans 0. Sacken, Proc. Ac. Nat. Sc. Phil. 1859, p. 220. 

 Antocha saxicola 0. Sacken, 1. c. 



Variable in size and coloring. Head grayish-brown ; rostrum 

 yellowish, sometimes infuscated ; palpi and antennas brown ; the 

 first joint of the latter sometimes yellowish. Thorax either 

 ochraceous, or brownish-gray, with some yellowish spots on the 

 humeri and pleurae ; in both cases with darker, more or less dis- 

 tinct stripes ; halteres pale, with a more or less brown knob ; feet 

 tawny, more or less dark, according to the general coloring of the 

 specimen ; coxse and base of the femora generally paler. Abdo- 

 men brownish or grayish-brown ; the genitals often, but not 

 always, yellow. Wings (Tab. I, fig. 11) with a whitish, somewhat 

 milky tinge, opalescent; the veins at the basis of the wings pale 

 yellow ; the other veins more or less dark brown ; stigma colorless. 



Hob. Europe and North America. I possess specimens from 

 Dalton, Ga. ; Washington, D. C. ; Trenton Falls, N. Y. ; Mon- 

 treal, Can. ; Lake Winnipeg, H. B. T. (Kennicott) ; Illinois (Le 

 Baron). The specimens from the north are generally larger. This 

 species has been noticed in Europe only since it was discovered and 

 described by me in North America ; it occurs near running water, 



