414 NORTH AMERICAN DIPTERA 



The literature dealing with the family is scattered and a thorough 

 revision of the American species is badly needed. The genitalia of both 

 sexes furnish good taxonomic characters. 



It is not an easy matter to decide the relationship of this family 

 but it seems probable that it originated from Taehinid stock, since the 

 postscutellum is strongly developed, and the scutellum usually short 

 and broad. The Tachinidffi with reduced mouth opening and mouth 

 parts are more or less bristled and are consequently easily distinguished. 

 However, as these are inhabitants of the Old World tropics we need not 

 discuss them here. More is said about the affinities of the old family 

 (Estridce under the Cuterehridce. 



KEY TO GENERA 



1. Apical cell closed and petiolate CEstrus Linnaeus 



Apical cell open 2 



2. Facial grooves only narrowly separated below (2) . . . .Cephalemya Latreille 

 Facial grooves very broadly separated 3 



3. Palpi absent; scutellum bare on apical third (3) Hypoderma Clark 



Palpi small, globular; scutellum pilose apically (1) . . .CEdamagena Latreille 



%^0'' 



t!|BIK!' 



CEstridse. — 1, CEdemagena tarandi; 2, Cephalemya abdominalis ; 3, Hypoderma lineatum. 



