272 J. M. ALDRICH. 



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



IVothoMympycnus Wheeler. 

 First .joint longer than the following iSyinpciiUS 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 exj)lain these : 

 Of those omitted in this table : 



Psilopus goes in Psilopodinus ; Gnamptopsilopus in Agonosoma. 



Hygroceleuthus falls into Dolichopus. 



Aptorthus is a synonym of Mesorhaga. 



Poeeilobothrus does not occur in North America, the species 

 being herein assigned to Sarcionus. 



Metapeladoneurus falls into Pelastoneurus. 



Aphantotimus is a synonym of Thrypticus. 



Dactylomyia falls into Neurigona. 



Macellocerus falls into Tachytrechus. 



Lasiargyra falls into Argyra. 



Lyroneurus falls into Diaphorus. 



Of added genera : 



Aphrosyhis and Teuchophorus are European genera found to 



occur here. 

 Coeloglutus was overlooked before. 



Parasyyitormon and Nothosympycnus 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. 

 Par hy drop horns falls into Hydrophorus. 

 Xaiithotricha is a synonym of Thrypticus. 



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

 favor of Syntormon. 

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

 coming Catalogue of North American Diptera. 



PEIiASTOI^ElIRUS, PARACL,IUS and SARCIONUS. 



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 



