DIPTEEA. 341 



ones brown on the outer side ; femora and tibiae pale yellow, the tarsi only slightly brownish. Wings 

 almost hyaline, the fourth vein bent halfway between the cross-vein and the apex. 



2 . Face wide, bent in the middle. 



Length 2-2-7 millim. 



Eab. Mexico, Teapa in Tabasco (E. H. Smith). 



Numerous specimens. The antennae in some specimens have a marked point on the 

 third joint, which is enlarged; others scarcely show this. In some males the hairs on 

 the last abdominal segment are noticeably large. 



SARCIONUS*, gen. nov. 

 This genus greatly resembles Pelastoneurus, but differs decidedly in the structure 

 of the face, which in the male is only one-tenth, in the female one-fifth or one-sixth, of 

 the entire width of the head. In the male it is a little wider in the upper and lower 

 parts, narrowest at or about the middle. The antennae have the same structure as in 

 Pelastoneurus, the arista being plumose. This character separates the genus from 

 Paraclius, with which, however, its relationship is less close. In these three genera, 

 I attach less importance to the shape of the last section of the third vein than to the 

 characters of the head. Some species are readily separated generically by the wing- 

 structure, but others are not. Type, S. lineatus (Aldrich). 



1. Sarcionus lineatus. 



Pelastoneurus lineatus, Aldrich, Trans. Ent. Soc. Lond. 1896, p. 312 \ 



Ilab. Mexico, Teapa in Tabasco (E. II. Smith). — Antilles, St. Vincent l . 

 Two females. 



2. Sarcionus flavicoxa, sp. n. {Pcecilobothrusflavicooca, Tab. VI. figg. 15, wing, 

 15 a, head, 6 .) 



<3 . Face narrowed below the middle, on account of an area of enlarged facets in the eye on this level, at 

 this place less than one-tenth the width of the head, its colour uniform greyish-white. Mouth small. 

 Palpi inconspicuous, yellowish. Antennae rather dark yellow ; third joint brownish-yellow, large, arista 

 with short plumosity. Front short, on account of the high insertion of the antennae, whitish-dusted. Cilia 

 of inferior orbit black. Thorax dark green, not very bright, the blackish spots in front of the wings 

 seeming in certain lights to continue round the front of it ; the white spots in the sutural groove 

 large, but not silvery ; pleurae entirely brownish-yellow, including the hind border ; halteres and 

 tegulse yellow, cilia of the latter black. Abdomen dull green, the incisures narrowly and faintly brownish ; 

 venter with a brown tinge ; hypopygium rather large, brown, the lamellae of the same colour, long and 

 pointed, the tips darker, the margins with black hairs. Legs yellow, the middle and hind coxae scarcely 

 infuscated at the base ; the middle tarsi slightly infuscated, the fore and hind ones yellow to the end. 

 Wings yellowish, slightly widened ; curve of the fourth vein just beyond the middle of the last segment, 

 quite gradual, still with a considerable concavity behind ; costa not thickened. 



9 . Face about twice as wide as in the male ; pleurae blackish, the sutures brown ; tarsi somewhat more 

 infuscated. 



Length 3*9 millim. 



Eab. Mexico, Teapa in Tabasco (H. H. Smith). 

 * From aapdoy, a flaw in an emerald, in reference to the narrow silvery face between the green eyes. 



