June, I9I2.] AlDRICH : BlOLOGY OF WESTERN EPHYDRA. 79 



This description, as will be seen, consists only of a few general 

 remarks about the puparium, comparing it with that of two other 

 species; it would perhaps scarcely be recognizable but for the refer- 

 ence to the exceeding abundance of the species in Great Salt Lake. 

 The description is especially unsatisfactory from the omission of a 

 striking and easy mark of distinction, the basal filaments of the anal 

 tube, which separates the species from all other American Ephydras 

 of which the early stages are known. But it is certain that Packard 

 was describing a strikingly small Ephydra common in Great Salt 

 Lake, and there is but one species, whether he described it well or not. 



Jones was dealing with specimens from Southern California, and 

 was naturally unable to identify them from Packard's description. 

 Mr. E. T. Cresson, Jr., examined Jones's' types and compared them 

 with material from Great Salt Lake ; he is inclined to retain the name 

 cincrca for a large variety, but my material does not justify this. 



Adult (PI. VII, Fig. i). — Length, 2.3 to 3.5 mm.; of wing 2 to 2.9 mm. 

 General color opaque gray, paler below and with a slight greenish tinge 

 above ; front moderately bright green ; legs infuscated, knees and greater part 

 of the tarsi yellow ; wing-veins yellow at base. 



Head of typical Ephydra shape, the face not shining below the antennae, 

 front large, shining green except when viewed from in front with nearly 

 frontal light, when it is ashy opaque ; lower half of front with scattered 

 minute hairs directed somewhat backward, no decussate small bristles ; no 

 noticeable impressions on front ; frontal orbits pollinose, gray, with three 

 bristles curving over the eye and a few small hairs arising between them ; 

 the edge of the front next the orbit is covered for a narrow space with a 

 duller pruinosity ; ocellar triangle pollinose, with two pairs of divergent 

 hairs behind the single pair of large, divergent bristles ; two vertical bristles 

 each side, the inner curving directly mesad, the outer almost exactly laterad ; 

 occiput opaque, orbits not different, with only a small row of hairs. An- 

 tennae black, gray pruinose, very short, rather far apart ; first joint hardly 

 visible, second nearly as long as third, with a slender erect hair at base and 

 a notch in apex above just behind the arista ; third without lateral hair, 

 arista almost basal, short, thick at base, moderately plumose under high 

 power. Face almost white all over, with scattered small black hairs and 

 a row of three or four divergent and upturned long hairs each side above the 

 middle, extending laterally close to the lower edge ; lower edge of face with 

 quite short and thin hairs hanging down, about the same in both sexes. 

 Cheek behind lower part of eye rather large, with small hairs and one or 

 two somewhat larger. Proboscis thick and short, black: palpi indistinctly 

 yellowish. 



Thorax opaque gray, with scattered small black hairs and the usual 



