373 



Family Megamerinidse 



Small, e]oni>ate, slender flies with petiolate abdomen and incras- 

 sate posterior femora. 



Head nearly spherieal, broader than high; front moderately broad 

 in both sexes; frontal bristles absent, the ocellars and verticals strong; 

 face very gently convex, without ^'ibrissfe; antenna? of moderate length, 

 decumbent. Thorax elongate and narrow, with bristles posteriorly; 

 mesosternum long, the posterior two pairs of legs approximate; sciitel- 

 lum short and broad. Abdomen elongate and elavate, the basal segments 

 slender and fused. Legs of moderate length, the posterior femora 

 strongly swollen and with bristles below on the apical half. Wings nar- 

 row; auxiliary vein absent; first vein ending- at basal third of the 

 wing; first basal cell long, the anal cell as long as the second basal, 

 more or less rounded apically. 



The single genus representing this family in America occurs in the 

 tropics. I have seen only four specimens collected on Barro Colorado 

 Island, Canal Zone, and Cresson had the same number from Costa 

 Rica. I found the specimens among rather thick foliage in moist places. 

 They resemble species of Sphegina (Syrphidae) although much smaller, 

 but, of course, the resemblance is only superficial. 



Syringogaster Cresson is our only genus and is represented by two 

 described species, both of which occur in Panama. 



I am not certain that this genus belongs to the I\legamerinid{B as 

 the species show striking differences from a species of Megamerina (so 

 named) in the American Mu.seum of Natural History. 



Syrinsogaster, wing, body, 

 (Cresson) 



