June, I9i6.] SwENK: NoRTH AMERICAN HlPPOBOSCID^. 131 



from Dallas on the red-tailed hawk (Buteo borealis), from Florida 

 by Johnson on the screech owl (Otiis asio asio), and from Haddon- 

 field, New Jersey, November 9, on the red-tailed hawk, also by John- 

 son. In Nebraska it has been taken at Brownville on the great 

 horned owl (Bubo virginiamis virginiamis) on December 30 by the 

 late Ex-Governor R. W. Furnas, and at West Point on the rough- 

 legged hawk (Archibittco lagopus saucti-johannis) in October, 1884, 

 by L. Bruner, these two specimens being before me. A third speci- 

 men at hand is labeled simply " Louisville, Kentucky." Apparently 

 the species is widely distributed in the eastern United States on our 

 commoner birds of prey. 



The published descriptions of O. aiiicricaiia, while sufficiently ex- 

 plicit that I believe I have correctly identified the species, are yet so 

 brief and general that a redescription of the species would be proper 

 at this time. 



Length 6-7 mm., the head and thorax alone measuring 4.5 mm., and the 

 distance from the front of the head to the tip of the wing measuring 10.5- 

 11.5 mm., the thorax being 3 mm. wide at the widest part. Head and thorax 

 brown. Head slightly elliptical, one and one third times as wide as long, the 

 face strongly narrowing anteriad, its width across the middle of the front 

 one and one third times as broad as the eyes at the same level, the elevated, 

 rather narrow orbital margins and the elevated, plano-convex lenticular vertex 

 polished, the depressed, subtrapezoidal median area opaque. A very few short 

 scattered bristles on the inner edges of the polished orbital margins. Clypeus 

 nearly five sixths as long as the front, dullish, the apical section rather broad 

 basally and very broadly and shallowly emarginate anteriorly, this emargina- 

 tion being really arcuate in form, so that the visible basal width along the 

 dividing sulcation is only a little over one third of the distance across the 

 emargination between the lateral apices. Antennary processes black, con- 

 spicuously black-haired. Palpi long, fully one and one half times as long as 

 the clypeus, yellowish to brownish in color, finely black-haired. Eyes satiny 

 black. Humeral processes short, bluntly pointed, about concolorous with 

 thorax above or the very tips somewhat paler. Mesonotuni with both the 

 longitudinal and the transverse lines rather deeply impressed, especially the 

 latter which are scarcely interrupted medially. Mesonotum not distinctly 

 hairy anywhere. Scutellum with the posterior margin weakly convex, laterally 

 thinly hairy, and with a distinct subapical rim, medio-longitudinally rather 

 broadly and shallowly depressed or impressed, giving the sclerite a slightfy 

 sub-bilobed appearance. Pleura above yellowish brown, below shading into 

 a pale yellowish concolorous with the flat, shining sternum, the latter with the 

 anterior angles feeble and concolorous with the rest of the sternum. Head 

 beneath pale yellowish, the labium whitish. Legs light brownish above and 



