314 NORTH AMERICAN DIPTERA 



blade of distinctive structure; ovipositor not extended, the female ab- 

 domen with bluntly rounded termination. 



The adults are found about excrement, carrion and decaying vege- 

 tation, in which the larvte live, and many of the species are very com- 

 mon. There are between forty and fifty described species from North 

 America. Melander and Spuler* and Dudat have dealt with the 

 species. 



KEY TO GENERA 



1. First and second basal cells separated 2 



First and second basal cells united (3, 5) Pandora Haliday 



2. Outer verticals present 3 



Outer verticals absent 5 



3. Anterior femora of both sexes with a close-set row of spinules ven- 



trally, never with stout spines or thorns (4, 6) Nemopoda Desvoidy 



Anterior femora never with such a row of spinules, often with coarse 

 spines, sparse hairs or more or less deformed 4 



4. No frontal bristles (7, 8, 9) JSepsis Fallen 



One frontal bristle; anterior femora never tuberculate. 



Meroplius Rondani 



5. Postocellar bristles long and strong; one frontal (1, 2). .Themira Desvoidy 

 Postocellars very weak; f rentals not developed Enicita Westwood 



* 1917, Wash. Agric. Exp. Sta.. Bull. No. 143. 



•(• 1925, Ann. Naturh. Mus. Wien, xxxix, pp. 1-153, and 1926, xl, pp. 1-110. 



t The genus Sepsidimorpha Frey I cannot separate from Sepsis and I do not consider the 

 absence of tubercles on the anterior femora of generic importance. Those species of Sepsis 

 which have a frontal bristle I would place in Meroplius even though the front femora are 

 armed beneath. 



