28 A REVISION OF THE NEARCTIC SCIOMYZIDAE 



I wish to express my obligations to the following individuals 

 for their instrumentality in securing the loan of material and 

 in the granting of other favors, without which I could not have 

 presented this ]3aper: Mr. C. W. Johnson, Boston Society of 

 Natural History; Dr. J. C. Bradley, Cornell University; the late 

 Mr. F. Knab, U. S. National Museum; Mr. W. L. McAtee, U. S. 

 Biological Survey; S. J. Hunter, University of Kansas; E. P. 

 VanDuzee, California Academy of Sciences; Mr. M. C. Van 

 Duzee, Mr. C. T. Greene, Mr. W. T. Davis, and Mr. N. E. Ciiddle. 

 The material credited to these sources is indicated throughout 

 this paper by self explanatory notation within [ ]. The illustra- 

 tion of the wings and the rough outlines of the profile of the 

 heads were prepared by the author. 



The species representing this family in our fauna, according 

 to the existing catalogues, were for the greater part segregated 

 into three genera, which were rather easily recognized on account 

 of their head and antennal structure, namely Sepedon, Sciomyza 

 and Tetanoccra. While several other genera were recognized, 

 mostly containing one or two species, they were not very well 

 understood, i e., Bischofia and Heterochila. 



I have not attempted a critical analysis or characterization of 

 the family. This has been done for the European species by 

 Hcndel in his revision, which should be consulted by our students. 

 In general thei-e will be no difficulty in recognizing tlic genera 

 and species lielonging to the family, especially the species of the 

 genera allied to Sepedon and Tetanocera, but those allied to 

 Sciotnyza are not so easily defined, especially the genera. The 

 family characters may be l;)riefly diagnosed as follows: 



The post verticals diverging or parallel, never converging; the 

 face in profile foi-ming a sharp, often very acute angle with that 

 of the oi'al margin; no vibrissae; arista generally pubescent to 

 densely plumose; all tibiae with preapical extensors, but without 

 other extensor bi'istles; the auxiliary vein compk^te to the costa 

 and well separated from the first. 



In separating the species fi-om those of the other acalyptrate 

 families, the following notes may be helpful; the Scathophagidae 

 have distinct vibi'issae; the Ortalidae and Trypetidae have no 

 preapical tibial bristles (excepting in Antoinohi): th(> Sai)n)- 

 myzidae ai-e all small flies with Ww ])ost veiticals converging, 



