June, 19I5-] OSBURN : STUDIES IN SyRPHID.^. 141 



States that there are two female specimens in the collection of the 

 Philadelphia Academy of Sciences. From Mr. H. S. Harbeck of Phila- 

 delphia I learn that he has ten specimens of arbustorum and that a 

 friend took a series of twenty last summer. Mr. V. A. E. Daecke, 

 of Harrisburg, Pa., writes that ten out of twelve from that region 

 are arbustorum. Mr. Frederick Knab, of the U. S. National Museum, 

 states that the species is now common about Washington, though 

 the earliest records are for 1908. 



The question has been raised by some of my correspondents as to 

 the specific distinctness of these two species. Without doubt they 

 are closely related, as may be judged from the amount of confusion 

 recently existing in collections. They are so similar in size, form 

 and general coloration that, without a careful examination, one would 

 unhesitatingly place them together — as we all did ! 



The difference in extent of the velvety bands of the third and 

 fourth abdominal segments is sufficient to separate the species, though 

 in the males some familiarity with this character may be necessary. 

 The differences in the abdominal markings are as follows : 



First and second segment. Similar, with sexual differences only. 



Third segment of male. Similar, though the velvety black bands 

 are somewhat wider in arbustorum than in nicigenii. 



Fourth segment of male. Dissimilar; a distinct transverse band 

 of velvet on the base of the segment and another, usually narrower, 

 in front of the yellow posterior marginal band in arbustorum, while 

 in meigenii the velvet is limited to a minute basal median spot (often 

 wanting) and an occasional trace of the velvet black in front of the 

 yellow hind border. 



Third and fourth segments of female. Dissimilar; in incigcnii 

 these are entirely shining except for the occasional presence of a 

 minute median basal spot of velvet and a mere trace of the same in 

 front of the yellow hind border, while in arbustorum there are distinct 

 bands of the velvet on the basal part of both segments as well as 

 similar bands in front of the yellow hind border. 



An easier character is found in the color of the basal joint of the 

 tarsus of the middle legs. In arbustorum this joint is yellow or 

 orange except at its extreme tip, which is sharply brown, while in 

 meigenii the whole joint is dark brown like the rest of the leg. 



It may be thought that these characters are unsatisfactory for the 



