306 Annals Entomological Society of America [Vol. XIII,. 



six species have been dropped as unrecognizable, eight have been 

 relegated to synonymy and twenty-four have been assigned 

 different generic names, leaving but twelve remaining 

 unchanged. In the following pages are given synoptic keys 

 to twenty-two genera, eighty-nine species and eight varieties. 

 Cresson's paper enumerates fifty-five species and seven varieties, 

 distributed among twenty genera. 



The family designation, Tetanoceridas, has been chosen 

 instead of the name Sciomyzidse, because Tetanocera Dumeril, 

 1798, antedates Sciomyza Fallen, 1820. Even the genera 

 Dictya Meigen, 1803, and Sepedon Latreille, 1804, have claim 

 for recognition prior to Sciomyza. The forms grouped about 

 Dryomyza are sometimes segregated as a distinct family, the 

 Dryomyzidae, but while they have a somewhat characteristic 

 habitus, their differences are hard to express in terms of family 

 value. 



In the following pages are given in dichotomic form identifica- 

 tion tables for the genera and species of Tetanoceridas known 

 from north of Mexico. Only in cases where genera or species 

 are not listed in Aldrich's Catalog a bibliography has been 

 included ; where species have been assigned to genera other than 

 in the Catalog the former name is given in parenthesis; page 

 references to Cresson's paper are quoted following his name. 

 Localities represented in my collection are designated by an 

 asterisk (*). 



The valves of the hypopygium, called paramera by Hendel, 

 sometimes afford splendid characters for identification. The 

 genitaha must be disengaged in order to obtain a view of these 

 appendages, which in old specimens can be readily accomplished 

 by relaxing and pulling down the hypopygium. Examination 

 of the valves, especially in species of Tetanocera, where they are 

 large, affords a ready means of certain identification. It may 

 be that such an examination of the American specimens referred 

 to T. elata, ferruginea and silvatica will disclose that these 

 European species do not occur in this country. 



With reference to the identification of other European 

 species, the extended distribution of some, such as Neuroctena 

 anilis, Melina nana and grisescens, has long been known. 

 Flies that have so distinctive and frequent a habitat as the 

 marshy shores of ponds often have a wide distribution. The 

 prevalence of European species on the Pacific slope is not 



