2 PROCEEDINGS OF THE NATIONAL, MUSEUM vol.70 



here included in the Chilosinae, thereby doing away with the Nausig- 

 asterinae. The genus is a highly modified one, but aside from its 

 peculiarities it shows the subfamily characteristics of the Chilosinae. 



The genus Alipumilio (new genus) is still more specialized than 

 Nausigaster^ inasmuch as the humeral calli are completely covered 

 by the posterior part of the head, and consequently the calli are 

 bare (a character heretofore recognized as peculiar to the Syrphi- 

 nae), but this genus shows unmistakable relationships with the 

 Chrysogasterini and is therefore retained in the Chilosinae. The 

 absence of the spurious vein also removes it from the Syrphinae. 



It must be understood that the characters used in the present key 

 are chiefly applicable to the South American fauna. A rather scant 

 representation of material permits the use of certain characters that 

 probably would have to be abandoned if a key were made for both 

 North and South America, or even if a larger representation of the 

 South American material were available. 



KEY TO THE SOUTH AMERICAN GENERA OF SYRPHIDAB 



A\ Antenna with a terminal style . cekioidinae. 



B\ Antenuifer less than half the length of first antennal joint. 



Cerioides Rondani. 

 B^ Antennifer longer than length of first antennal joint. 



Monoceromyia Shannon. 

 A'. Antenna with a dorsa arista. 



B^. The humeral calli and the inter-humeral region destitute of pile (if 

 spurious vein is absent see Alipumilio, Chilosinae) ; discal crossvein 

 placed well before middle of discal cell ; spurious vein always present ; 

 no stigmatical cross vein ; male, as well as female, with five visible 



abdominal segments sybphinae. 



C\ Squamae, squamal cilia and plumula well developed, the cilia of the 

 lower squama equal to at least half the length of haltere; flies 

 usually of broad form. 

 D\ Face entirely black. 



E\ Face much broader than length of arista. 



F*. First antennal joint as long as second Melanostoma Schiner, 



F^. First joint much longer than second Braziliana Curran. 



E'. Face not broader than length of arista Xanthandrus Verrall. 



D'''. Face largely yellow. 



E^. Metasternum long pilose. 



F'. Oral opening about twice as long as broad. 



Claraplumula, new genus. 

 F^. Oral opening four or more times as long as broad. 



Fazia, new genus. 

 E^ Metasternum bare. 



F\ Wings without villosity, glassy in appearance; head large, 



inflated Scaeva Fabricius. 



F^ Wings villose, head normal S3rrphiis Scopoli. 



C. Squamae, squamal cilia, and usually the plumula, considerably reduced 

 (the upper squama usually vestigial, lower squama very narrow, 

 lower squamal cilia less than half the length of haltere, usually very 

 short; plumula sometimes absent) ; slender flies. 



