4 PROCEEDINGS OF THE NATIONAL MUSEUM vol.69 



markings for specific characterization, particularly the yellow ab- 

 dominal spots in certain species. These have proved very vari- 

 able, especially in the female, where they may be completely obscured 

 by the bluish-black coloration. The following remarks pertain to 

 the most involved tangle that has arisen in this study. 



In Williston's " Synopsis^ of North American Syr'phidae " he 

 described elongata as a new species and recorded two positive speci- 

 mens from New Hampshire and Pennsylvania. Later Williston^ 

 placed elongata as a synonym of angustiventris Loew. These two 

 specimens, now in the National Collection, prove to be two species. 

 The New Hampshire one is a female of angustiventris and is most 

 probably the specimen upon which Williston based the synonomy. 

 At this time he evidently redetermined the Pennsylvania specimen 

 as anthreas^ for this specimen now stands in the collection with the 

 label '■'■Xtjlota anthreas Walk." in Williston's handwriting. (This 

 specimen and others like it are treated here under the name ejuncida, 

 variety elongata. See Xylota ejuncida two paragraphs below.) 

 Subsequent writers, however, have not accepted Williston's synonomy 

 and have continued to recognize elongata (=female angustiventris) 

 as a valid species. Metcalf in his " Syrpidae of Ohio " separates 

 " elongata " from angustiventris on the ground that it lacks the 

 yellow spots which are present in angustiventris. But, as Williston 

 writes and as the material at hand shows, only the male amgurstiven- 

 tris has yellow spots, whereas the female has the abdomen entirely 

 dark ; furthermore in Metcalf 's records he has only males for angus- 

 tiventris and females for elongata. The large third antennal joint 

 which Metcalf notes for " elongata " is a striking characteristic of 

 both sexes of angustiventris. 



The real Xylota anthreas Walker, incorrectly described from a 

 single male, proves to be the same species that Coquillett later de- 

 scribed as Xylota fascialis. The type specimen of anthreas is some- 

 what discolored but the yellow face and yellow abdominal markings 

 (which typify the type of fascialis) are easily discernible. Walker, 

 however, makes no mention of the partly yellow face and states that 

 the sides of the abdomen «are " adorned with large steel blue spots." 

 This mischaracterization has proved very misleading; while at the 

 same time Williston's conception of anthreas has given rise to the 

 so-called anthreas of subsequent publications. It may be that Walker 

 had some other species before him at the time he described anthreas^ 

 but this hardly seems to be the case as no North American species 

 fits his description, 



Xylota anthreas, in Williston's sense, as already indicated, proves 

 to be a different species. Williston determined a female Xylota as 



»Ent. News, vol. 3, p. 146, 1892. 



