June, I9i6.] SwENK : NoRTH AMERICAN HlPPOBOSCID^. 127 



brown, the costi only moderately thickened beyond the end of the first vein 

 which joins the 'osta a little before the first crossvein, the costal border of 

 the marginal cell one and one third times as long as the costal border of the 

 first submarginal cell, the first basal cell over twice as long as the second 

 basal cell. 



Say states that the numerous species described in the paper in 

 which Olfcrsia albipcnnis and Ormthomyia nebulosa, pallida (=an- 

 chincuria) and coiifluciita were described (Journ. Acad. Nat. Sci. 

 Phila., iii, pp. 9-54 and 73-104), were collected chiefly by himself 

 while on the Major Long Expedition. Inasmuch as the party spent 

 the period from September 9, 181 9, to June 6, 1820, at Engineer Can- 

 tonment, near the present site of the town of Blair in eastern Ne- 

 braska, and since he notes " Ardca hcrodias," " Strix nebulosa" and 

 " Sylz'ia sialis" (respectively the three species of birds from which 

 the first three above-mentioned flies were collected) as present at 

 Engineer Cantonment during his stay, it seems highly. probable that 

 the types of these species were collected at that place. O. confliiciita, 

 taken from " Ardca caudidissuna," was probably taken lower down on 

 the Missouri river or further east. With O. nebulosa and O. pallida, 

 their hosts become so uncommon outside the Missouri valley that it 

 is almost certain they could not have been taken by Say at any point 

 further west. 



O. albipennis is here redescribed froin three specimens all collected 

 at Lincoln, Nebraska, two April 18, 1892, on a black-crowned night 

 heron (Nycticorax nycticorax naevlus) by L. Bruner, and the third 

 April 13, 1900, on a green heron (Butorides vircscens z'irescens) by 

 J. S. Hunter. Say's specimen was from a great blue heron (Ardca 

 hcrodias subsp.). The coincidence of locality and host, together 

 with the perfect agreement of my specimens with Say's description, 

 especially in such characters as the pale humeral tubercles, whitish 

 wings, size, etc., make it as certain as one can reasonably be that the 

 above-described species is truly albipcnnis Say. As Say's type is 

 lost, I select the above-mentioned specmien from the green heron to 

 stand as the neotype of the species. 



A variety of O. albipcnnis, having the scutellum with the median 

 longitudinal sulcus very weak, so that the scutellum is not at all sub- 

 bilobed in appearance, and the vertex with a large, shallow anterior 

 concavity (this is feebly marked in typical albipcnnis) is represented 



