Dec.,i92i Bulletin of the Brooklyn Entomological Society 123 



As in Chrysidid^, the abdomen of Nausigaster is composed 

 of four visible segments (sometimes three in Chrysididse). It 

 is rimmed with a projecting edge and can be doubled under 

 and against the thorax, enclosing the ventral aspect of the lat- 

 ter; all of the chitinous parts of the body are thickly punctured 

 and have a metallic reflection; a scale-like projection of the 

 thorax is present near the base of the wing. 



The wing venation is fairly similar to that of the Chilosinse 

 except for the almost complete absence of the anal furrow. 



MICRODONTIN^. 



Table of Genera of Microdontin^. 



1. Third vein with an adventitious branch extending downward 



into the discal cell 2. 



Third vein simple ; abdomen spatulate Mixogaster. 



2. Abdomen spatulate, face swollen and prominent below. 



Rhopalosyrphus. 



Abdomen ovate or with parallel sides; face gently arched; 



tarsi short and crassated Microdon^ 



CHILOSIN^, new subfamily. 



This subfamily merges into the Xylotinse, through Myiolepta, 

 Brachyopa, et al., so gradually that it is with some difficulty 

 separated therefrom. However, for practical purposes, the old 

 character of the position of the discal crossvein works very 

 satisfactorily. These subfamilies are the last to appear in the 

 table of subfamilies and by having the other groups excluded, 

 the matter of separating these two is fairly simple- 



Several species of Cynorrhina (Xylotins), C. pictipes and 

 nigra, because of the position of the discal crossvein, are treated 

 in the table of Chilosinae. On the other hand the genus Fer- 

 dinandea, apparently very closely related to Chilosia, appears in 

 the table of Xylotinae, because the discal crossvein joins the dis- 

 cal cell at, or beyond, the middle. 



Table of Genera of Chilosinae. 



I. Alula greatly reduced, being narrower than the second basal 

 cell; anal furrow very short or absent; abdomen either 



