438 C. R. OSTEN SACKEN'S PRODROME 



brownish border ; the tliorax is clothed with a dense whitish pollen, which, with the reddish 

 ground color visible through it, produces the appearance which Wiedemann calls lilac red- 

 dish {lilacino-ruh'xJna ; observe that he calls lilac brownish, the thorax of T. ynolestus). 

 These characters easily distinguish well preserved specimens of this species from T. techis ; 

 at the same time they are merely differences in coloring, and not plastic characters, and 

 therefore unsatisfactory. The, as yet, unknown male of this species may afford some char- 

 acters distinguishing it from the very well-marked male of T. tectus. 



T. s^dcifrons Macq., is this species, as the description of the wings proves. The furrow 

 on the front, mentioned by Macquart, is adventitious, and not a specific character. 



At the time when Fabricius described this species (1805), there existed a much older 

 Tahanus variegatus, that of DeGeer ; as the latter, however, is very probably the same as 

 Chrysops costatus Fabricius, I do not see any necessity for proposing a new name for 

 T. variegatus Fab. 



9. Tabanus molestus. 



Tahanus molesttis Say, Jouni. Ac. riiil., Ill, p. 31, 1 ; Wiedcmanii, Auss. Z\v., I, p. 12.5, 21. 



Female. Palpi reddish, clothed with minute black hairs ; ftice white, with white hairs 

 (in older specimens yellowish) ; front brownish gray, with a In-own spot in the middle ; 

 frontal callosity chestnut-brown, a little longer than broad, prolonged upwards as a spindle- 

 shaped line. Antenna? black, with some vestiges of reddish on the first and second joints ; 

 sometimes the third joint is reddish at the base ; its upper angle more or less projecting. 

 Thorax brown, with well marked white longitudinal lines, formed by short white hairs on a 

 whitish ground color ; the reddish scutellum in well preserved specimens appears white 

 from a white pollen and white pubescence. Pleura) white, with white hairs (yellowish in 

 older specimens) ; a stripe of black hairs between the root of the wings and the humerus. 

 Abdomen dark brown, often nearly black ; on the first segment there is a white spot under 

 the scutellum ; hind margins of segments with narrow white borders, expanding into white 

 triangles in the middle ; the triangle on the second segment is small, hardly reaching the 

 middle of the segment ; those on the third and fourth segments are the largest ; those on 

 the fifth and sixth segments are again smaller ; the white posterior borders of the segments 

 expand on the sides, so as to occupy the whole lateral margin. Venter densely clothed 

 with a whitish microscopic pubescence ; incisures whitish ; last segments more brownish. 

 Legs black or brown ; til:)i;\3 reddish Ijrown, blackish towards the tip ; in well preserved 

 specimens the four posterior tibia) show a dense, white pul)escence. Wings subhyaline, 

 slightly tinged with pale brownish ; stigma brown ; very faint, hardly apparent vestiges of 

 brown clouds on the crossveins and at the bifurcation of the third vein ; first posterior cell 

 not coarctate. Length, 18-20 mm. 



Ilab. District of Columbia, Kentucky (Bee Spring in June, F. G. Sanborn), Georgia, 

 Missouri. Ten females. 



The very large size of the white triangles on the third and fourth abdominal segments, in 

 contrast to the small size of the ti-iangle on the second segment and the white scutellum, 

 helps to distinguish this species from those to which it has a superficial resemblance. The 

 stripes on the eyes of the female are very like those of T. trbnacidatus. 



