OF THE TABAXIDiE OF THE UXITED STATES. 435 



As the original T. ahdominalis Fab. had the first posterior cell dosed, we will begin by 

 describing, as typical, the specimens partaking of this character, without inquiring, for the 

 present, whether it is specific or merely adventitious. 



Female. Face pale yellowish gray with pale hair on the checks ; palpi dusk}^ yellowish, 

 with short black hair, which gives them a darker appearance ; front rather narrow, brownish, 

 mixed with gray; frontal callus longer than broad, chestnut broAvn or dark brown, with a 

 somewhat spindle-shaped pi'olongation above ; antennoe red ; basal joints clothed with short 

 black hair; third joint rather broad, with a rather rectangidarly projecting upper angle; 

 annulate portion black, the region immediately preceding it often more or less brownish. 

 Thorax brownish gray, with alternate gray lines and darker strij^es ; the former, in well 

 preserved specimens, are clothed with short, golden yellow hairs (visible under the lens 

 only). Pleurae of a dingy yellowish gray, with hairs of the same color ; a fringe of black- 

 ish hair above the root of the wings. Scutellum bro■\\^lish at the base, more reddish pos- 

 teriorly. Abdomen brownish rufous, with whitish triangles in the middle of the segments, 

 those on segments 2-4 differing but little in size, that on segment five smaller ; a distinct 

 black spot clothed with black pile intervenes between the apex of the triangle on the second 

 segment and the hind margin of the first. The hind margins of the segments have borders 

 of fulvous hair on reddish yellow ground, becoming broader laterally ; the last segments 

 are darker, the black pile upon them being more dense ; the sides of the segments usually 

 have blackish spots, overgrown with black pile, in their anterior corners. Venter yellowish 

 rufous ; last segment with some blackish hair. Legs : front coxfB clothed with gra}' pollen, 

 darker towards the tip ; a tuft of whitish hairs near the base, on the outside ; front femora, 

 distal half of tibiae and tarsi, dark brown ; proximal half of tibia? yellowish white ; middle 

 legs brown, tibite more or less yellowish white on the proximal half; hind femora brown, 

 beset with pale hairs ; tibio3 yellowish brown, paler at base, and with a fringe of black hair 

 on the outside ; tarsi brown. Wings with a distinct brownish tinge ; crossveins at the base 

 of the second, third and fifth jDosterior cells, as well as the bifurcation of the third vein, 

 with distinct brown clouds ; first posterior cell closed, the third and fourth veins uniting a 

 short distance before the margin. 



I have three female specimens answering this description ; two from the Middle States 

 (pi'obably District of Columbia) ; one from Illinois ; unfortunately, only one of them has 

 the markings on the abdomen well preserved. Length, 18-20 mm. 



Having thus described the specimens which come nearest to Fabricius's type, I will pro- 

 ceed to notice the aberrant specimens which I have before me, whether they be varieties 

 or species. 



I have fourteen females and three males (principally of my own collecting in the District 

 of Columbia ; also from Maryland, Pennsylvania, New Jersey), which resemble the above 

 described T. ahdominalis very much, but have the first posterior cell open, although 

 strongly coarctate. All the females, at the same time, have a distinctly broader front. In 

 other respects, I do not perceive any prominent distinctive characters. The abdominal tri- 

 angles in these specimens seem to be narrower and more yellowish, the abdomen appears 

 more uniformly rufous, without distinct black spots on the sides, etc., but as, of the typical 

 form, I have only a single specimen with well preserved abdominal markings, I cannot de- 

 cide whether the differences just stated are permanent or only accidental. The males have 

 subhemispherical heads, with a well marked dividing line between the large and small 



