410 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 46. 



STIBASOMA DYRIDOPHORUM, new species. 



Body and legs dark, ^vith black vestitiire, the abdomen with yellow 

 lateral patches at base; wings black, with the tips and a discal spot 

 hyaline. 



Female. — Antennae black; third joint with an obtuse but promi- 

 nent tooth on the lower side, and above with, a long, thick process, 

 slightly enlarged toward apex, rounded at tip, and reaching nearly 

 to the apex of the third amiulation. Frons narrow, nearly parallel- 

 sided, the frontal callosity convex, elongate subovate, as mde as the 

 frons, continued upward by a raised Une which becomes obsolete 

 toward the vertex. Face whitish pruinose. Cheeks with long black 

 ciliation. Palpi black. 



Thorax blackish brown, clothed with black hair, two indistinct 

 reddish lines on the dorsum ; humeri and ante-alar callosities yellow- 

 ish brown; pleura? brown, with black hair, a small tuft of snow-white 

 hair close before wing insertion. Scutellum reddish brown, darker in 

 the middle, mth black hair (mostly rubbed off). 



Abdomen dorsally reddish brown, the first and second segments 

 pale, with dense lateral tufts of long sulphur-yellow hair and a mixture 

 of black and yellow hair on the disk (somewhat abraded), the black 

 hairs predominating; hind margin of second segment and all of the 

 succeeding segments densely black haired. Venter ferruginous, the 

 second and third segments with large quadrate lateral patches of 

 dense sulphur-yellow hair, which are joined to the yellow patches 

 of the dorsum ; the remaining vestiture f erru^nous, with some black 

 hairs intermixed at the sides posteriorly, a tuft of black hair medianly 

 at the base of the second segment. 



Legs reddish brown, the front tibiae thickened and blackish on the 

 distal two-thirds; vestiture black, the hind tibiae with long black 

 cihation with ferruguious luster on outer side and shorter bright fer- 

 ruginous ciUation on inner side; limd tarsi with ferruginous hair. 

 Claws black. PulvilU and empodia yellow. 



Wings rather narrow, smoky black, a triangular hyaline spot in the 

 middle of the second submarginal cell, an elongate hyaline spot occu- 

 pying most of the discal cell and extending well over into the second 

 basal cell. Halteres with a pale greenish knob. 



Length: Body about 14 mm.; wdng 12 mm. 



Trinidad, West Indies (P. L. Guppy). 



Type.— C&t. No. 16362, U.S.N.M. 



A single specimen sent by Prof. F. W. Urich, with the note "Fol- 

 lowed the collector persistently." 



The abdomen is more slender and tapering than usual in this genus, 

 but this is no doubt due to the fact that the specimens had not fed. 

 The obtuse tooth on the under side of the third antennal joint is 

 present also in S. willistonii, although developed to a less degree. No 

 such tooth exists in S. fulvohirtus. 



