2 CATALOGUE OF NORTH AMERICAN DIPTERA. 



Articles on biology and anatomy have been especially sought for. 

 However it may be in other orders, the vast economic importance of 

 the Diptera will not allow us to study the cabinet specimen only. 



In economic literature some of the minor references have been 

 omitted, where no new facts appeared to be brought out. Every one 

 knows that a considerable part of economic literature is of this class, 

 and it is properly so, being prepared for a public who do not read 

 entomological journals. The omitted articles are generally very brief 

 ones, and strictly " popular " in form. 



There are some European writings on the biology of species occur- 

 ring both in Europe and North America, which are not included. It 

 was not deemed feasible to enter in detail into the European literature. 



Method. In form I have followed Osten Sacken quite closely. 

 Few explanations will be needed. It is to be understood that the 

 species is described with more or less fullness under each reference, 

 unless an explanation is given indicating something else (as " oc." for 

 occurrence; " syn." for synonymy; "notes," etc.). Still, I am aware 

 that there are some cases where I failed to note the limitation. 



The locality is given with each reference. This is of importance 

 in two ways. First, in furnishing the type locality, as closely as given 

 by the describer ; second, in case a certain reference proves to have been 

 due to an erroneous identification, it enables the reader to deduct that 

 one and leave the rest unaffected. Every entomologist who acquires 

 any familiarity with the literature of a group comes to trust some 

 writers much more fully than others. It is only by separating the 

 localities in the bibliography that these allowances can be made, with- 

 out looking tip all the literature. 



Synonymy and nomenclature. Those synonyms which had been 

 made out by Osten Sacken I have accepted in toto. More recently, 

 a considerable number have been made out by the examination of types 

 of Walker, Bigot, and others. These appear to be well-founded. In 

 addition to these, a large number have been made out from descrip- 

 tions, nearly every dipterist of the country having contributed some- 

 thing in this direction. I have generally quoted these, although we 

 may expect that some will ultimately prove erroneous. In a few 

 cases I have expressed doubt, or an adverse opinion. The authority 

 for synonymy is generally given in brackets, unless expressed in the 

 context. 



In the selection of names, priority is accepted as the first test ; it 

 may, however, be overshadowed by uncertainty as to the application 

 of the older name. I have found comparatively few cases of specific 

 names that were hard to decide, but among genera there are many 

 which may be argued about as well one way as the other. I began 

 with the intention of being very conservative ; but I have been drawn 



