W. M. DAVIDSON 39 



margin of the segment briefly' at the posterior angles. Fifth segment shining 

 gray; on the second and third segments there is a narrow shining median stri])e. 

 Pile white, on opaque portions black and wliite intermixed. 

 Length, 6.7.5 mm. 



One specimen, Canada wliicli apparently lielongs with the 

 two males. 



Ho](jtype (male) and allotype (female) in the U. S. National 

 Museum. 



This species chffers from M. ubscurum and il/. nhscurmn var. 

 rostratum in the fact that the head is not produced below beak- 

 like: from M. chaclopodd in the abdominal s]:)ots of the female 

 being distinctly' Ijronze, and not greenish, and in the pollen of the 

 face of l)oth sexes l)eing non-punctate. 



Melanostoma obscurum Say, varietj- rostratum Bigot (Text-fig. B.) 



Male. Antennae brownish-black; joint three oval, twice as long as broad, 

 yellow below at the base, sometimes the whole underside 3'ellowish; arista 

 black, bare. Vertical triangle bluish-black, black pilose. Frontal triangle bluish- 

 l)lack, obscurely shining, black pilose. Face grajnsh pollinose in indistinct 

 ripple-like formation, a median rather narrow shining bluish-black stripe not 

 reaching the antennae; facial pile black above, white below. Cheeks shining 

 black with scant whitish pollen and white pile; facial tubercle protruding 

 considerably beyond antennal tubercle, the epistoma protruding Ijcj^ond the 

 facial tubercle; giving the face in })rofile a rostrate appearance; below the 

 antennae gently concave. Eyes red, bare, contiguous, ten facets. Occi])ut 

 white pollinose, pile white below, fuscous above. 



Thorax and scutellum bluish-graj', shining; pile fulvous, scutellar pile long, 

 black and fulvous mi.xed; on the humeri a tuft of black hairs. Wings equal to 

 or exceeding the body length, hyaline. Halteres dull graj'. Tegulae white, 

 fringe fulvous. Legs black, apical third of four anterior femora testaceous; 

 iiind knees yellow; anterior tibiae except a broad ring near the apex, whole 

 of midtlle tibiae, base and apex of hind tibiae, basal joints of all tarsi, testace- 

 ous; hind metatarsi slightly incrassate; pile of legs mosth' light; all tibiae with 

 a row of about eight long slender black hairs. 



First abdominal segment shining bluish-graj'. Second segment oi)a(jue 

 black along the side with a shining silvery-gray spot, which is produced along 

 the anterior border, again at the middle of the segment, and reaches along the 

 sides three-quarters the length of the segment. Third segment opaque black, 

 with two shining bronze trigonal spots; these spots reach on the lateral mar- 

 gins tw^o-thirds the length of the segment; second and third segments also 

 with a narrow median shining strij)e. Fourth segment shining bronze, on its 

 posterior half with two narrowlj' separated slightly obliciue opaque t)lack spots, 

 which reach the margin of the segment just before the jwsterior angle. Fifth 

 s(>gmenl shining bronze. Hypojjygium shining black. Venter shining ])urplish- 

 l)lack. Pile of abdomen white, on the oi)a(iue areas short black and white 

 uitermixed. Sides of the abdomen nearlj' parallel. 

 Length, (j.o to 9 mm. 



TR.\X.S. AM. EXT. SOC, XLVUI. 



