THE DIPTEROUS GENUS DOLICHOPUS IN NORTH AMERICA. 221 

 No. 159. DOLICHOPUS CRENATUS Osten Sacken. 



Hygroceleuthus crenatus Osten Sacken, Western Diptera, 1877, p. 312. — 



Aldrch, Kansas Univ. Quart., 1893, vol. 2, p. 24, pi. 1, figs. 27, 27a; 



American Naturalist, 1894, p. 35 (courtship). — Wheeler, Proc. Calif. Acad. 



, Sci., vol. 2, 1899, p. 3, pi. 1, fig. 4.— Melander and Brues, Biol. Bull. 



vol. 1, 1900, p. 131, figs. 



Male. — ^Length 5-6 mm.; of wing 4.5-5 mm. Face wide, of 

 nearly equal width, silvery white; front shining green. Antennae 

 (fig. 159a) black; first and second joints yellow on lower half, with a 

 large smooth yellow protuberance on inner side; first joint very long 

 and with stifle, long black hair ; second and third of nearly equal length, 

 taken together about as long as first; third scarcely longer than wide, 

 pointed at tip; arista thick, clothed with long dense pubescence. 

 Lateral and inferior orbital cilia yellowish, the lowest ones deeper 

 yellow and slightly flattened; the black cilia descend below the 

 upper third of the eye. 



Thorax green with coppery reflections, which sometimes cover most 

 of the dorsum. Abdomen green, usually with coppery reflections'^ its 

 sides with white pollen. Hypopygium black; its lamellae of mod- 

 erate size, oval, with a narrow black border on the apical margin; 

 apex jagged and bristly, fringed above with black hairs, sometimes a 

 few near the base yellowish. 



Fore coxae yellow, with a green stripe on outer edge of its posterior 

 side, their anterior surface with minute delicate white hairs and a 

 few black ones along inner edge. Middle and hind coxae black with 

 yellow tips; the trochanters usually with a brown spot. Femora 

 and tibiae yellow. Middle femora each with one preapical bristle; 

 hind pair with a row of bristles of increasing length, ending in the 

 usual preapical bristle, without cilia below. Posterior tibiae a little 

 thickened and compressed, with a shallow glabrous groove on inner 

 side, the glabrous stripe on upper surface distinct, but broken by a 

 few hairs. Fore and middle tarsi about as long as their tibiae, infus- 

 cated from the tip of the first joint; still the base of some of the other 

 joints yellowish; first joint of fore tarsi as long as the remaining four 

 taken together, fourth the shortest. Calypters, their cilia, and the 

 halteres yellow. 



Wings (fig. 159) grayish; broad, narrowed from the middle to the 

 anal angle, which is still prominent; costa thick with a rather long 

 knotlike enlargement at tip of first vein; last section of fourth vein 

 considerably bent a -little before its middle; hind margin of wing 

 deeply indented at tip of fifth vein, which is bent backward near the 

 middle of its last section almost at a right angle. 



Female. — Face wide, grayish white; arista nearly as thick as in the 



male, but the antennae smaller; wings of nearly normal shape, 



without an enlargement of the costa, rather evenl}^ rounded on hind 



margin, indented at tip of fifth vein; cilia of the calypters usually 



187329—21 1.5 ' 



