KEVISION OF THE TWO-WINGED FLIES OF THE GENUS 

 COELOPA MEIGEN IN NORTH AMERICA 



By J. M. Aldrich 



Associate Curator, Division of Insects, United States National Museum 



The present revision has been prepared as the result of recent 

 correspondence with Mr. J. E. Coilin, of Newmarket, England, who- 

 has furnished information relating to synonomy and has also sup- 

 plied the Museum with determined European specimens; from his 

 data and the specimens it appears that the North American members, 

 of the genus have been misidentified to a large extent. Two species- 

 from the Bering Sea region, formerly considered to be identical 

 with European forms, are here described as new. 



All the species appear to breed in the kelps, and are found only 

 on seashores where seaweeds of this group are washed up. This 

 limits the distribution of the flies on the Atlantic side to the northern 

 coast, with Rhode Island as the southern terminus, but on the 

 Pacific the kelps extend much farther south, so that one species of 

 the fly is common at least as far south as San Diego, Calif. 



Genus COELOPA Meigen 



Coelopa Meigen, Syst. Besehr., vol. 6, 1830, p. 8. — Haliday, Ann, Nat. Hist., 

 vol. 2, 1839, p. 186. — Westwood, Introd. Mod. Classif. Ins., vol. 2, Synops., 

 1840, p. 144. — Stenhammar, Skaudinaviens Copromyzinae (Kongl. Vetensk. 

 Akad. Handl.) 1853 (1855), p. 317.— Loew, Hon. N. Amer. Dipt., vol. 1, 1862, 

 p. 42. — ScHiNER, Fauna Anstriaca, Diptera, vol. 2, 1864, p. 319. — Cole and 

 LovETT, List Dipt, of Oregon (Proc. Cal. Acad. Sci., ser. 4, vol. 11) 1921, p. 

 320. — WiLLiSTON, Manual N. Amer. Dipt., ed. 3d., 1908, p. 317. — Malloch, 

 N. Amer. Fauna No. 46, 1928, p. 214, keys to species. 



Fucomyia Haliday, Ann. Nat. Hist., vol. 2, 1839, p. 186. — Westwood, Introd. 

 Mod. Classif. Ins., vol. 2, Synops., 1840, p. 144. 



The genotypes of Coelopa and Fucomyia have been remarkably 

 confused, owing to the misidentification of Musca fHgida Fabricius. 

 This was the only species included in Goelopa by Meigen in 1830, but 

 Haliday in 1839 recognized that it was not the true frigida of 

 Fabricius, and gave the name pilipes to Meigen's species, which thus 

 attains the status of genotype and has been so accepted by Mr. 

 Collin, although the matter has not been discussed in print. 



No. 2808.— Proceedings U. S. National Museum, Vol. 76, Art. 11 



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