264 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



IZa&.— Manitou, Colo., August 18. One male and three females. 

 A uote which I took when the specimens were alive describes the eyes 

 as greenish-purple, with a bluish-purple cross band across the middle; 

 in the male, the facets above the cross-band are the larger ; in the female, 

 those below. 



P. scolopax is very like the figure of Poecilognathus thlipsomyzoides 

 Jaennicke (Keue exotische Diptern, tab. i, f. 11) ; and although it ap- 

 pears from the description that it is a different species, it is eqaally evi- 

 dent that both are most closely related. I do not see any sufficient 

 ground for separating this species from Phthiria; at any rate, it is singu- 

 lar that Mr. Jaennicke, in his definition of his new genus Poecilognathus, 

 does not even mention Phthiria. He says the venation is that of Thlip- 

 somyza; but that genus has the first posterior cell closed, while Poecilo- 

 gnathus, according to the figure, has it open. 



3. Phthiria egerminans Loew, Centur., x, 47. — California. 



4. Phthiria notata Loew, Centur., iii, 19. — California. 

 I have not seen these two species. 



5. Phthiria humilis n. sp., $. — Grayish-black; sparsely beset with 

 pale grayish-yellow pile on the thorax, and with white pile on the abdo- 

 men and the under side of the head ; legs and antennae black ; wings 

 hyaline. Length 4-5 mm . 



The grayish-black ground-color of the epistoma, cheeks, and front is 

 clothed with a grayish pollen, more yellowish-gray on the occiput ; oral 

 margin and chin beset with white pile, silvery in a certain light ; occiput 

 with yellowish pile; antennae black. The grayish-black ground-color 

 of the thorax is but very little concealed above by a covering of pale 

 grayish -yellow downy pile, more dense anteriorly ; pleurae opaque, 

 almost glabrous ; abdomen sparsely beset with long, erect, whitish pile, 

 more dense on the sides ; hal teres brownish-yellow ; legs black; femora 

 with some whitish pile ; wings hyaline ; posterior costal cell (interval 

 between the auxiliary and first vein) yellowish in its latter half; veins 

 dark brown, except near the root. 



Hab. — Los Guilucos, Sonoma County, Cal., July 4. A single male. 



In life, the smaller facets on the lower part of the eye were of a darker 

 color than those above. 



This species can be, without difficulty, referred to Phthiria, although 

 in its coloring and its pubescent body it differs from the other Ameri- 

 can species of the genus. The flattened antennae, truncate at the end, 

 the long proboscis, and the venation, are those of Phthiria. But the 

 second submargirial cell and third posterior bear no stumps of veins on 

 their outside, as they do in P. sulphur ea aud scolopax. 



Geron. 



- The described North American species are : — 

 holosericeus Walker, List, ii, 295. — Georgia. 

 senilis Fab.,- Wied., i, 357. — West Indies (Wied.) ; Texas (Macq.). 



