WillistOD.] 'J>^0 piay I'J, 



resuscitated, and have also recognized an interesting new species of Seno- 

 gaster Mac, hitherto known only from South America. Since the publi- 

 cation of the catalogue four new genera have been described by M. Bigot 

 and the writer, making in all sixty -two genera now known from North 

 America. As regards the distribution of these genera twelve are pecu- 

 liar to our fauna, viz : Eupeodes, Copestyliim, Iladromyia, Eugerdamyia, 

 Earhinamallota, Teuchocncmis, Ptcrallastes, Polydonta, Crioprora, Somu- 

 la, Merapioidus, and Mixogaster. The first four of these, with Cata- 

 bomba, have never yet been found in the Eastern States, while the fol- 

 lowing are not yet known west of the one hundredth meridian, 

 viz : Triglyphus, Pyrvphmna, Doros, Ocyptamus, Rhiiigia, Teuchocnemis, 

 Pierallastes, Senogaster, Somula, Temnostoma, and Mileda. Of these no 

 doubt the distribution will yet be found more extensive. Indeed the wide 

 distribution of species and genera of the family over our continent will 

 not readily be paralleled by any other family of insects. 



In the present paper I have given a list of all the described species 

 known west of the one hundredth meridian. These with the species de- 

 scribed as new, reach yet but eighty-six ; of them fifty-four are known 

 only fi-om the West, while thirty-tw'o, or over one-third, are distributed 

 from the Atlantic to the Pacific regions. 



Five genera, of one or two species each, namely : Triglyphus, Pyro- 

 pJimna, Copestylum, Arctophila, and Pierallastes, are unknown to mc ; 

 • their systematic positions have in consequence been wholly draw'n from de- 

 scriptions and figures. They, together with such species as are unknown 

 to me, are preceded by an asterisk. An exclamation point indicates that 

 the localitj^, or localities, preceding it are given from specimens that I 

 have examined. It has not been deemed necessary to repeat any of the 

 bibliographical references or synonomy that are given in Osten Sackeu's 

 catalogue, except such as will facilitate the identification of species. The 

 specimens which I have examined in the preparation of this paper, from 

 Washington Territory, Oregon, and Kern County, California, were col- 

 lected by Mr. H. K. Morrison ; from Mendocino county, California, by 

 Mr. O. T. Baron, and from Wyoming, Colorado, and Kansas, by Mr. E. 

 W. Guild and myself. The species that I have identified, or described, or 

 that have been previously recorded from the West, are printed iu small 

 capitals. 



I desire to express my thanks to Mr. W. H. Patton and Drs. G. II. Horn 

 and H. A. Brous, for kind favors in the preparation of this paper. To 

 Baron C. R. von Osten Sacken, of Heidelberg, I am much indebted for 

 his kindly interest and advice. 



The folknving table of generic groups is based essentially upon that of 

 Schiner's in his Austrian Diptera. It seems impossible to improve its 

 general features so far as our American genera are concerned. 



