220 ERNEST A. BACK. 



Legs and coxae black, the articulations more reddish, the short pile 

 and all the bristles black; claws black, reddish at base; pulvilli pale. 

 Halteres yellowish, base of the peduncle blackish. Wings black, all 

 the cells with a paler central area, the fourth posterior cell closed and 

 slightly petiolate, the other posterior and submarginal cells open, the 

 anal cell closed at the margin. 



9 • — Osten Sacken's collection possesses two females, and that of 

 Prof. C. W. Johnson several more. They differ considerably from the 

 male, and might easily be taken for a different species; the head, an- 

 tennte, in varying degrees, and the thoracic dorsum, are reddish-brown 

 and not black as in the typical male. The pruinose fasciae on second 

 and third segment of abdomen are bright golden instead of white, and 

 sometimes the ground color of these segments, excepting the posterior 

 margins, reddish. The legs are usually brownish-red, the femora being 

 darker and more or less blackened on the femora; wings brown, the 

 costal vein more yellowish. 



Type. — The types are located as follows: Dasypogon tristis, 

 British Museum; Dasypogon quadrimaculatus , University, 

 Turin, Italy; Dizonias phoenicurus and bicinctus, M. C. Z.; 

 Ospriocerus albifasciatus , Am. Ent. Soc. Phila. 



Habitat. — St. Augustine, Georgiana and Enterpirse (C. W. 

 Johnson, May 15), and Turkey Lake, (Orange Co., Aug. 29, 

 E. A. Back), Fla. ; Opelousas, La. (C. W. Johnson, June 3); 

 N. M.; Dallas, Texas (Osten Sacken) ; Mexico and Central 

 America (Biologia). 



In determining this species one must allow for a large range 

 of variation. The antennae may be wholly black, or the 

 distal part of the first segment, the whole of the second 

 and the basal portion of the third may be red in varying 

 degrees. The dorsum of thorax may be wholly black or red- 

 dish. The abdomen may be entirely black, with or without 

 the white fasciae (though I believe the absence of these is due 

 to rubbing or greasing) or the posterior margin of the fourth 

 and the following segment entire, may be red, and sometimes 

 lines or small areas of red may be found on the second and 

 third segments. A specimen may have the thoracic dorsum 

 and the distal portion of the abdomen red, or the dorsum may 

 be black and the abdomen still red. The bristles of the coxse 

 may be wholly black, almost wholly white, or an even mixture 

 of the two colors. 



