2 b DIPTERA OF NORTH AMERICA. 



Latr., 9. Anthrax Scop., 10. Argyromceba Schin., 11. Exopro- 

 SOPA Macq. 



Moreover, Macquart has founded his genus Oncodocera on a X. 

 A. species, and described a X. A. species among his Anisotamice, 

 though it seems to be an alien there. Mr. Walker described some 

 X. A. species, which he placed under the genera Apatomyza Wied. 

 and Phthiria Mcisr. 



Fam. XXII. SYRPHIDAE. 



Charact. — Three basal cells much prolonged ; third longitudinal vein sim- 

 ple ; a spurious longitudinal vein (vena spuria) between the third 

 and fourth longitudinal veins ; fourth longitudinal vein united at 

 its end with the third ; no intercalary veins. Hypopygium unsym- 

 metrical ; no empodium. 



This is one of the most extensive families and includes about 

 eighty genera, the enumeration of which seems to be superfluous 

 here. A distribution into sections, however desirable, proves 

 exceedingly difficult. To divide the family into genera with an 

 antennal bristle and genera with a terminal style would be no great 

 gain, since the number of the latter is very small. 



I know the following genera to occur in X. A. : Volucella 

 Geoffr., Temnocera St. Farg., Microdon Meig. (— Aphritis 

 Latr.), Cert a Fabr., Sericomyia 31eig., Tropidia Meig., Syritta 

 St. Farg., Xylota Meig., Mallota Meig., Brachipalpus Jlfacq., 

 Milesia Latr., Sphecomyia Latr., Somtjla Macq., Chrysotoxum 

 Meig., Mixtemyia Macq., Mallota Meig., Helofhilus Meig., 

 Eristalis Latr., Plagiocera Macq., Ocyptamus Macq , Baccha 

 Fabr., Sphegina Meig., Rhingia Fabr., Orthoneura Macq. ( = 

 Cryptineura Big.), Paragus Latr., Cheilosia Meig., Chryso- 

 chlamys Pond., Doros Meig. , Pidea Macq. (= Enica Meig.), 

 Melithreptus Loew (= Sphserophoria Macq.), Mesogramma 

 Loew, Syrphus Fabr., SciEVA Fabr., Platycheirus St. Farg. 



It results from the remarks of some authors that species of the 

 genera: Pipiza Fall., Chrysogaster Meig., Fpistrophe Walk., Po- 

 hjdonta Macq., and Merodon Latr. occur with certainty in X. A. 



The genus Chymophila Macq. founded on a X. A. species must 

 be entirely blotted out from the list of genera. For it is evident 

 that Bigot is right in stating that the specimen on which it was 



