140 ERNEST A. BACK. 



cepted by Fabricus, Wiedemann, Say, Macquart, Walker, and 

 only a few genera were added up to the time when Loew 

 began his memorable work upon this family. 



Loew laid the real foundation for thorough work upon the 

 Asilidae in his monograph "Ueber die Europaischen Raubfiie- 

 gern (Diptera Asilica*)," supplemented by him in many later 

 publications, especially in the " Bemerkungen iiber die Fam- 

 ilie de Asiliden**" and "Die Dipteren Fauna Sud^ Africas,t" 

 Schiner's "Fauna Austriaca,'!" "Die Wiedemann's chen Asil- 

 iden,||" and "Neue o|der wenig bekannte Asiliden des K. zool. 

 Hofcabinits in Wien,§" are as a whole rendered invaluable as 

 a survey of all the genera of Asilidae down to 1866, and for the 

 analytical keys for their identification. 



The foregoing mentioned works deal wholly or largely with 

 species foreign to this country. While Say, the first American 

 to work upon this family, and several foreign writers, described 

 a few species from this country, Loew and Osten Sacken were 

 the greatest contributors to our present knowledge of the Lep- 

 togastrinae and Dasypogoninae, up to the time when Dr. 

 Williston began his studies. Although Osten Sacken has 

 described many less species than Loew, his untiring efforts in 

 getting together collections from this country for Loew to 

 study should not be undervalued. It is to the credit of his 

 foresight that the types of Loew's North American species 

 were deposited in the Museum of Comparative Zoology. Loew 

 published his works chiefly between the years 1862-1874. 

 Perhaps one can get the best idea of the amount of work done 

 by these two gentlemen from the fact that at the time Osten 

 Sacken published his Catalogue in 1878, of the 115 species 

 from the territory covered by this paper, Loew had described 

 62.6%, and Osten Sacken 19.1%; thus making a total of 81.7%, 

 as the result of their labors. When we consider that the types 

 of all these species are now at the Museum of Comparative 



*Linn. Ent., Vol. II, III, IV; Suppl. in Vol. V (1847-1851). 

 ** Berlin, 1851. 

 t Berlin, 1860. 

 t 1862-64. 



II Verb. Zool. Bot. Ges., 1866. 

 gVerh. Zool. Bot. Ges., 1867. 



