270 ENTOMOLOGICAL NEWS. [Oct., '06 



diately on getting settled in this country he began to organize 

 things for extensive dipterological research. He pubhshed (in 

 1859) a catalogue of the described North American Diptera ; 

 he collected a large amount of material in the order ; he made 

 the acquaintance of most of the collectors in various parts of 

 the country, and had them send him their Diptera ; most of 

 his accumulations he sent to Loew in Guben, Prussia, for de- 

 scription, reserving only a few families, principally the Tipu- 

 lidse and Tabanidse, for himself; he also established relations 

 with the Smithsonian Institution which resulted in the publi- 

 cation of a large part of the descriptive matter prepared by 

 Loew and himself in the four volumes called by the general 

 title of " Monographs of North American Diptera " ; in short, 

 it may be said that for some twenty-one years nearly all the 

 work done on the order was directly due to the tremendous 

 energy of Osten Sack en. Toward the close of the period, 

 after visiting the principal type collections of Diptera in 

 Europe, he published a second catalogue of North American 

 Diptera, this time critical in character and exhibiting the 

 actual status of the order in a manner which for clearness, 

 completeness, and absolute mastery of the subject must for- 

 ever remain an unapproachable model for later workers in the 

 order. Osten Sacken had practically created himself all the 

 main subject matter of the catalogue ; hence the impossibility 

 of any later entomologist ever occupying a similar position 

 with regard to it. 



In addition to the Smithsonian monographs and his two 

 catalogues, Osten Sacken 's Prodrome to a Monograph of 

 North American Tabanidse, published by the Boston Society 

 of Natural History, and Loew's Centuries of North American 

 Diptera (one thousand new species, published in Germany), 

 embody the principal results of his labors. 



As a fitting climax to his achievements, Osten Sacken suc- 

 cessfully conducted a rather difficult and delicate negotiation, 

 by which Loew was reimbursed for his labors on the North 

 American material, and surrendered it all to the Museum of 

 Comparative Zoology at Harvard, at that time much the best 

 depository in the United States for such material. Osten 



