142 Journal New York Entomological Society, [^'o'- xxiii. 



separation of the species, yet in the examination of nearly 200 speci- 

 mens of arbiistonim and 100 of mcigcnii I have first separated them 

 on the basis of the abdominal markings and then on the leg character 

 and have found my determinations to agree in every case. 



At first it occurred to me that these differences might be seasonal, 

 indicating different broods, but the facts that the two species occur 

 together and that both are found throughout the season preclude any 

 such possil)ility. ^ 



Now it is of interest to note that in all the collections personally 

 examined or reported to me there are no specimens dating back 

 farther than 1906. This brings up the question whether E. orbns- 

 tornm is a recent addition to our fauna or whether it has been here 

 all the time and has been overlooked by all former students of the 

 Syrphidse. Obviously the answer to this question is not easy, unless 

 one has sufficient faith in the infallibility of the older workers in this 

 group. However, it would seem that if arhiistonim is not a recent 

 acquisition it should be found among the older collections, even if 

 not properly identified. As this species does not, to my knowledge, 

 appear in any of the older collections I believe the assumption is 

 warranted that it has been introduced into 7\merica rather recently, 

 has found the environment congenial and has spread rapidly and 

 widely in a comparatively short time. 



E. arbiistonim occurs in Europe, N. Africa, Asia Minor and 

 Siberia. The records at hand for the American distribution are as 

 follows : 

 New York. — Staten I. ( Wm. T. Davis) ; Long I. (several collectors) ; 



Manhattan I. and the adjoining mainland (R. C. O.) ; South Lake 



and East Jewett, Catskill Mts. (Wm. T. Davis) ; Ithaca (Cornell 



Univ. Coll.) ; Carmell. 

 New Jersey. — Palisade, Ft. Lee, Lakehurst and Ramsey (R. C. O.) ; 



Fairlawn and Sewall (E. L. Dickerson). 

 Pennsylvania. — Philadelphia (H. S. Harbeck and V. A. E. Daecke) ; 



Swarthmore and Hazelton (E. T. Cresson, Jr.) ; Harrisburg (V. 



A. E. Daecke) ; White Mills. 

 Maryland. — Baltimore (W. L. Dolly, Jr.) ; Lakeland and College 



Park (F. Knab) ; Bethesda (J. C. Crawford) ; Cabin John, Cabin 



John Bridge and Plummers Island (R. C. Shannon). 

 District of Columbia. — Washington (F. Knab) ; Rock Creek (R. C. 



Shannon). 



