466 C. R. OSTEN SACKEN'S PRODROME 



spots on each segment, gradually- diminishing and becoming more rounded posteriorly ; at 

 the middle of the hind margin of the segments a small fringe of yellowish hair, sometimes 

 assuming a subtriangular shape. Venter yellowish, often more or less blackish, clothed 

 with a thin grayit?h pollen and yellowish hairs. Legs yellowish red, base of femora, to a 

 greater or less extent, black ; tarsi black, except the base of the four posterior ones, which 

 is reddish ; tips of front tibia; blackish. Wings hyaline ; crossveins and bifurcation of the 

 third vein clouded with brown ; first posterior cell broadly open. 



3Me. Face dark grayish, beset with blackish hair ; antennae darker ; third joint more 

 narrow ; thorax clothed with denser blackish pile, gray lines less distinct ; legs black, tibiae 

 and base of four posterior tarsi reddish brown. Length, 12-16 mm., both sexes being 

 rather variable in size. 



Huh. United States and British Possessions; not rare. (Massachusetts; Maine; De- 

 troit, Mich.; Illinois; Quebec, Canada, etc.) 



I have seen Walker's T. notaUlis in the British Museum. 



48. Tabanus a£Eiiiis. 



Tabanus affinis Eirby, Fauna Bor.-Amer., IV, p. 313, 1. 



Female. Eyes pubescent; palpi brownish yellow, with short black hairs ; second joint 

 moderately stout at base ; face yellowish gray; antenna3 dark red, third joint black on its 

 latter half, its basal portion rather broad, the upper angle projecting and the excision well 

 marked ; front dark yellowish gray, somewhat convergent anteriorly, clothed with black 

 hair ; callosity black (seldom reddish), rather small for the size of the species, with a usually 

 spindle-shaped prolongation ; ocellar tubercle brownish black, very distinct. Thorax dark 

 grayish black with a tinge of brownish, and with more or less distinct gray lines ; antealar 

 tubei'cles reddish. Sides of the first four abdominal segments rufous, which color leaves a 

 black stripe in the middle, narrowest on the second segment, and expanding on the third 

 and fourth (in some specimens the fourth segment is almost black, with only a rounded 

 reddish spot on each side ; in others the red color invades even the fifth segment) ; on 

 each of the segments two to five, on the black stripe, there is a triangular whitish yellow 

 spot (formed by pollen overgrown with pubescence), the last of which, on segment five, is 

 subobsolete ; hind margins of segments yellowish, with a fringe of yellowish hairs ; better 

 preserved specimens show, on segments two and three, traces of lateral oblicjue 3'ellowish 

 spots. Venter rufous, last two or three segments black. Front legs black, base of tibiie 

 reddish ; on the hind legs the end of the femora, the tilsia; and tarsi are rufous ; tibia? with 

 a fringe of black hairs. Wings with a fiiint brownish gray tinge, more marked in the cos- 

 tal cell and across the central crossveins; first posterior cell broadly open. Length, 17- 

 20 mm. 



Hah. Northern United States and British Possessions. I have about three dozen 

 specimens from Fort Good Hope, Lake Athabasca, Portage and Slave Lake, Lake Winnipeg, 

 Lake Superior (Michipicoten) ; Bethel, Me. ; White Mts., N. H. 



The antennae are sometimes black, with a trace of red at the base of the third joint only. 

 The identification cannot be doubtful, as this is the largest among the allied species. 



