MAY FLIES AND MIDGES OP NEW YORK 115 



and finely spinulose (fig.21). These strange veinless wings are 

 not especially thin or delicate, but on the contrary are rather 

 thickened, the costal margin being especially thickened and per- 

 haps folded. The halteres (fig.20) or the structures which oc- 

 cupy the usual position of the halteres, are not of the usual 

 pedicel and knobbed type common among D i p t e r a , but are 

 minute lobe or scale-like processes, appearing like rudiments of 

 metathoracic wings ; like the mesothoracic wings, they are rather 

 thickened and finely spinulose; they are widest at the base and 

 taper to a rounded tip ; they average .08 mm. in length. Abdomen 

 with nine segments, tapering gradually posteriorly; mottled 

 blackish and gray above, lighter below, palest laterally; a few 

 scattered, small, wholly inconspicuous hairs, the body appearing 

 glabrous; external genitalia consisting of a pair of large, con- 

 spicuous, strong, articulated claspers (fig.24) which are covered 

 with a pubescence. 



Female. Length 2.5 mm., thus being % longer than the male; 

 this extra length is all in the abdomen, which is markedly larger 

 than the abdomen of the male in every way. The head and 

 thorax are narrower than the robust abdomen, which is sub- 

 cylindrical, tapering only slightly posteriorly. Eyes as in the 

 male very small, very widely separated, and hairy. Antennae 

 only 4-segmented. Mouth parts essentially as in the male, with, 

 however, appreciable differences in shape; the labrum-epipharynx 

 is narrower at base, and is more pointed apically; the labium 

 with paraglossae separated farther ba-ck and slightly narrower. 

 The reduced wings and halteres like those of the male, the wings' 

 length .85 mm., slightly elongated. The abdomen consists of nine 

 segments mottled blackish, with conspicuous white sutural spaces, 

 caused by the distension of the abdomen. The external genitalia 

 are inconspicuous. There is a short, emarginate dorsal plate with 

 rounded tips and a pair of lateral processes. There appears to 

 be no extrusible ovipositor. 



Pupa of female. A single pupa taken with the imagines from 

 a tide pool. Length 2.5 mm. Immediately recognizable as pupa 

 of the female from the similarity in size, shape and markings. 

 Abdomen just as in the adult in regard to size, shape, color 

 and markings. The antennae, legs and wings are folded on the 

 lateral and ventral aspects of the anterior part of the body, and 

 extending backwards to (hardly reaching) the posterior margin 

 of the second abdominal segment. There are no external tracheal 

 gills or elongated spiracles (breathing tubes). There are -no 

 bristles nor special clinging organs. The pupa is of a very simple, 

 unmodified, unprotected type. 



