OF THE TABANID.E OF THE UNITED STATES. 469 



Some of these groups of specimens, especially the groups 3 and 4, mav really belong (o 

 different species, although I confess myself unable to characterize them as such to my own 

 satisfaction. They all have the same characteristic comparatively narrow and hardly 

 excised third antennal joint ; nor do I perceive any appreciable difl'erence in the shape of 

 the front or of the palpi. Some of them even have a few black hairs on the cheeks and on 

 the first joint of the palpi, but not nearly so distinctly as the specimen fi'om Labrador of 

 the group No. 1. 



51. Tabanus illotus n. sp. 



Female. E3'es pubescent ; front rather broad, slightly converging anteriorly, brownish, 

 mixed with gray, beset with black hair ; callosity black, nearly square, its linear proknga- 

 tiou above but weakly marked, usually appearing as an ill deiined oblong daik spot. Face 

 and cheeks of a rather pure grayish white, with white hairs ; palpi stout, pale yellowish, 

 with small black hairs. Antennte : third joint moderately broad and moderately excised, 

 with a well marked upper angle ; its color is more or less dark reddish, its distal half black. 

 Thorax blackish, with faint gray lines, antealar tubercles usually reddish, pleurje gray, Avilh 

 long, wdrite hairs. Abdomen blackish ; on the second segment two obliquely placed whitish 

 (in rubbed off specimens pale reddish) lateral spots, not touching the hind margin (the 

 whitish pollen and pubescence covering them reach the margin); on the third segments 

 two much smaller and rounded spots, of the same color ; on the following segments two 

 still smaller whitish, rather faint spots, visible only in well preserved specimens, and with- 

 out any reddish under them ; Moi\e of these spots are in contact with the hind margin of 

 the segment ; between these lateral spots triangular intermediate spots contiguous to the 

 hind margin are more or less visible, especially on the second and third segments. The 

 venter is covered with a delicate white pollen and with minute whitish hairs ; its ground 

 color is black, with more or less reddish in the middle, and a blackish stripe upon it. Coxas 

 and femora black, with a whitish pollen and long white hairs ; front tibiae reddish yellow, 

 black towards the tip ; middle tibia3 altogether reddish, the hind tibifB reddish brown ; all 

 the ti])ia3 beset with whitish hairs, the fringe of the last pair consisting sometimes of white, 

 sometimes of black hairs, or of both mixed ; tarsi brown. Wings suljhyaline ; f\iint brown- 

 ish clouds on the central crossveins, at the base of the second posterior cell and en the 

 bifurcation of the third vein; stigma brown. Length, 12-14 mm. 



Hah. Fort Eesolution, Hudson's Bay Territory (R. Kennicott) ; Yukon River, Alat-ka 

 (Kennicott); Eed River of the North (Scudder). 1 have a dozen specimens before me. 



This species is easily recognized among others by the rather conspicuous spots on the 

 second and third abdominal segments, while the spots on the following segments are smaller 

 and much less visible. In many specimens a reddish ground color shines through the 

 spots on the segments two and three, while it never appears on the following segments. 

 The faint clouds on the crossveins are also a good distinguishing character. 



I have two specimens from Fort Resolution, one from Lake "Winnipeg (Scudder), one from 

 Quebec (Belanger), two from Labrador (Caribou Island, Straits of Belle Isle, A. S. Packard), 

 one from Anticosti (Verrill),and one from Minnesota, all of which have the face and checks, 

 as well as the hair upon them, somewhat yellowish, instead of pure grayish white or white ; 

 the small black hairs on the palpi are denser, especially towards the tip, making the palpi 



MEMOIRS BOST. SOC. NAT, HIST. VOL. H. 118 



