272 J. M. ALDRICH. 



45. First joint of fore tarsus shortened in the male. 



IVothosynipycnus Wheeler. 

 First joint longer than the following SynipciiUS Loew. 



Since I prepared the table of genera of this family for Dr. Willis- 

 ton's Manual, many changes in the genera have occurred. The fol- 

 lowing notes explain these : 



Of those omitted in this table : 



Psilopus goes in Pdlopodinus ; Gnamptopsilopus in Agonosoma. 



Hygrocelenthus falls into Dolichopus. 



Aptorthus is a synonym oi' Mesorhaga. 



Pcecilobothrus does not occur in North America, the species 

 being herein as.signed to Sarcionus. 



Metapelastoneurus falls into Pelastoneurus. 



Aphantotimus is a synonym of ThrypfAcus. 



Daetylomyia falls into Neurigona. 



Macellocerus falls into Tachytrechus. 



Lasiargyra falls into Argyra. 



Lyroueurus falls into Diaphorus. 



Of added genera : 



Aphrosyhis and Teuchophoriis are European genera found to 



occur here. 

 Coeloglutus was overlooked before. 



Parasyntonnon and Nothosympycnas are new genera by Wheeler. 

 Sarcionus, Phylarehus and Xanthina are new genera by myseli'. 



Of recent genera not included : 



Xiphandrium, assigned to our fauna by Wheeler, does not 

 really occur in North America. 

 Drepanomyia is a synonym of Hypocharassus. 

 Parhydrvphoriis falls into Hydrophorus. 

 XaMhotricha is a synonym of Thrypticus. 



Synarthrus, revived by Wheeler, has been rejected by Mik, in 

 favor of Syntonnon. 

 The bibliographical references will be given in full in my forth- 

 coming Catalogue of North American Diptera. 



PEIiASTOMElIRUS, PARACLIUS and NARCIONUS. 



These three genera are in some cases difficult to distinguish from 

 each other; briefly, Pelastoneurus and Sarcionus have a plumose 

 arista, while that of Paraclius is hardly pubescent; the face in 



