168 PROCEEDINGS ENTOMOLOGICAL SOCIETY 



ceptiou, and Enmusca is proposed for it in this paper. More- 

 over the form is indicated as belonging with the Mesera- 

 brininae rather than with the Muscinae. 



Eitniusca corvina was found in the north of Russia to deposit 

 not over two dozen large eggs on dung. These eggs are 

 about 1.5 mm. long, not including an elongated curved ap- 

 pendage about two-thirds as long as the egg proper, which 

 acquires a dark color before hatching. The hatched maggot 

 is first stage, and it transforms directly to the third stage, 

 omitting the second stage, in the same manner as Mesembrina 

 mystacea. In the south of Russia this species was found to 

 breed in exactly the same manner during early spring and 

 rarely in summer, but almost exclusively in summer it was 

 found to have a different style of egg, lacking the appendage 

 and like that of Dasyphora, but proportionately much larger, 

 which it hatches in the uterus, and further carries the maggot 

 in uterus to third stage, omitting the second stage entirety, 

 as before, and practically in this point only differing from 

 Dasvphora. I am inclined to believe in Portchinski's obser- 

 vation that two species are not mixed here, but I cannot sup- 

 press a strong doubt due to the total difference in the egg. I 

 might admit oviposition under cool conditions and larviposi- 

 tion under warm conditions in the same species, perhaps, pro- 

 vided the form of egg were similar in both cases, and this 

 of itself seems a great deal to assume in these flies. But with 

 the difference in the eggs it seems almost insuperable. Yet 

 the muscoid flies have specialized in all sorts of directions to 

 an extent hardly to be dreamed of by those who have not 

 paid great attention to their study, and for this very reason I 

 do not dare to denounce any observation, however extraor- 

 dinary, without the most thorough investigation beforehand. 

 The extreme similarity of the two forms in the adult proves 

 nothing, as we know. Thus there is a very large possibility 

 that two forms are confused here, and that the females be- 

 lieved to be Eumusca corvina and which carried the maggot 

 in uterus to the third stage, are a distinct form that appears 

 in the south of Russia only after warm weather sets in. 

 Eumnsca cotvina is known to be a northern form of boreal 

 tendency, and is not recorded to my knowledge from more 

 southern regions than central Europe, except in the present 

 instance and excluding a doubtful Egyptian record, but if so 

 the southern form may just as well be distinct. Robineau- 

 Desvoidy describes three species in his posthumous work 

 which were so similar to corvina that he acknowledges him- 



