EXPLANATIONS 



NECESSARY FOR THE USE OF THE CATALOGUE. 



A Star (*) before a specific name means that the species is to be 

 found in the collection of the Museum of Comparative Zoology, 

 in Cambridge, Mass. These stars are omitted only in the family 

 Cecidomyidae. 



All interrogation (?) before a specific name means that its position 

 in the genus is doubtful; an interrogation before a synonym, means 

 that the synonymy is uncertain. 



An exclamation after a synonymy, means that I have seen the type 

 of the description. I have used this sign whenever I deemed it 

 necessary to inform the reader of that fact; but the absence of 

 that sign does not necessarily mean that I have not seen the type. 



Synonymies. The authority for each synonymy is given after it, in 

 brackets; where no authority is mentioned, my own is assumed. 



Genera. Species which I do not know, may sometimes not be placed 

 in the right genera; tliis applies especially to the species from 

 Mexico and the West-Indies. 



Loew, in litt. All the data, which I obtained from Mr. Loew, either 

 by letter, or In looking over his North American collection (during 

 my visit in Guben, in September 1877), are quoted in that way.' 



M. C. Z. Museum of Comparative Zoology in Cambridge, Mass. 



Localities. It will be noticed that, in some cases, the localities 

 marked in the catalogue, differ from those which are found in 

 Dr. Loew's Centuries of North-American Diptera. These discre- 

 pancies are not errors, or omissions, bid corrections. 

 In this Catalogue (as well as in my earlier list), I have not included 

 those species of earlier authors, which were marked simply ,,America". 

 New- York is always meant for the State of that name, not for the city. 



