THE CANADIAN ENTOMOLOGIST. 9 



there is no absolute uniformity in the length of the aristal joints, though 

 not much discrepancy. 



All the rest of my specimens, from various localities throughout the 

 United States, are larger, reaching twelve and a half millimetres in length 

 and none of them as small as the largest of the ones described. The 

 pollinose bands of the abdomen are usually broader on the second and 

 third segments, the wings in none so strongly infuscated proximally, and 

 in most the infuscation is more or less obsolete ; the antennae vary from 

 red to black, the second joint of the arista in the female varies from one- 

 third to three-fourths as long as the third joint ; in the male from one-half 

 as long to longer. The dorsal thoracic stripes vary from very slender 

 ones in Colorado specimens, to broader and more distinct ones in New 

 England, North Carolina, and Southern Californian ones. Specimens from 

 Carolina and New England have the basal part of the venter yellowish 

 red, with moderately large spots on the sides of the basal segments above* 

 A specimen from Wyoming has the thoracic dorsum strongly pollinose, and 

 the bands of the abdomen unusually broad. Two others from^California 

 have the second joint of the arista very short, not a third of the length o^ 

 the third, the wings scarcely at all infuscated in front, and, unlike all the 

 other specimens, the cheeks do not have black hairs, but yellow pile ; 

 other specimens from California, however, are like the eastern ones in this 

 respect. Yet another, rubbed (female) specimen, from Connecticut, differs 

 in having the sides of the face distinctly narrower, considerably narrower 

 than the median portion. The bristly hairs on the sides of the face vary 

 not a little in size ; those of the described specimens leave a more bare 

 space below on the inner side, that is less, or not at all, apparent in the 

 larger specimens. 



The value of these various characters I confess myself unable to 

 decide. Only this much seems certain, no, or little reliance can be placed 

 upon the comparative lengths of the aristal joints ; and the second joint 

 is always longer and more bent in the male than in the female. 



I think there can be little doubt but that this is Say's species ; his 

 " large, obsolete, reddish brown spot near the base " of the abdomen is 

 not usually, though frequently, present. The synonymy of G. philadel- 

 phica seems equally certain. The species must be closely allied to, pos- 

 sibly identical with G. fasciata Meigen, of Europe, the larvae of which 

 have been found in nests of Bombtcs terrestris and Megilla retrusa, where 

 the flies deposit their eggs. A specimen from the Boston Society of 



