ART. 9 AMERICAN XYLOTINE SYEPHID-FLIES SHANNON 5 



this species, and based his description of anthreas in his " Synopsis of 

 Syrphidae " upon this specimen. Walker wrote that the arista of 

 anthreas was black; Williston stated that the arista of his specimen 

 was yellow at the base. The yellow base of the arista has been taken 

 as the chief point of diagnosis for anthreas in subsequent keys of the 

 species of this genus. A certain specimen of the Williston collection 

 bearing the locality " White Mountains, Jackson, N. H." (Williston 

 gives only "New Hampshire" in his Synopsis) and standing under 

 the species anthreas^ is in all probability, the same as that upon which 

 Williston based his description. But, in this specimen, the arista is 

 not yelloAv at base but dark brown along its entire length. Finally, 

 it proves to be conspecific with the " Pennsylvanian " specimen, 

 which Williston described under elongata and subsequently rede- 

 termined as arnthreas. Williston's anthreas then becomes ejuncida 

 elongata Williston. 



In Xylota ejuncida Say, the yellow abdominal markings appear 

 to be very variable, especially in the female, at times becoming en- 

 tirely obscured by a bluish-black metallic coloration. As the " Penn- 

 sylvanian " specimen of '"'' elongata'''' and Williston's specimen of 

 " anthreas " differ from ejuncida only in the color of the abdomen — a 

 variable character — it is here proposed to consider them as a variety 

 of ejuncida. Since the "Pennsylvanian" specimen Avas one of the 

 types of elongata., the name elongata is retained for the varietal name 

 for the dark-bodied form of ejuncida. 



Xylota haton Walker, formerly placed as a synonym of ejuncida 

 Say, proves to be Xylota fraudulosa Loew, over which it has priority. 



The status of the species involved in this complication is as 

 follows : 



Xylota ejuncida Say, Amer. Entom., vol. 1, pi. S ; compl. Works, vol. 1, p. 15. 



A species recognized in this paper. 

 Xylota anthreas Walker, List III, 1849, p. 556. Synonym, Xylota fascialis 



Coquillett. 

 Xylota angustiventris Loew, Centuries 6, 58. A recognized species. Female 



usually determined as elongata Williston. 

 Xylota subfasciata Loevp, Centuries, 6, 57. A recognized species. Sometimes 



determined as ejuncida Say. 

 Xylota quadrimaculata IjOew= ejuncida Say. 

 Xylota annulifera Bigot= ejuncida Say. 

 Xylota elongata Wii.i,iSTON=angustiventris Loew and dark-bodied ejuncida Say, 



recorded here as Xylota ejuncida elongata Williston. 

 Xylota anthreas Williston (not Walker)— ejuncida elongata Williston. 

 Xylota elongata of authors=female angnstiventris Loew. 

 Xylota anthreas of authors=female Mton Walker? and ejuncida Say. 

 Xylota flavifrons Walker. 



Synonyms : Xylota. communis Walker and ohscura Loew. 



Williston thought flavifrons might be elongata — angustiventris. 



