W. I). HUNTER. 261 



The present part will he followed in these Transactions by por- 

 tions dealing with the subsequent natural groups of the order. The 

 next will include the species of the group Homodactyla in the sense 

 of Brauer. 



The territory covered by this catalogue is the Continent of South 

 America north to the Isthmus of Panama, with the neighboring 

 islands. This brings about the inclusion of the Island of St Vin- 

 cent, which, although properly of the West Indian group, is not 

 sufficiently separated from that continent to offer tangible faunal 

 differences. It must be admitted that, in some respects, it would 

 have been desirable to have included in this catalogue all of the 

 West Indian and Central American species, so that with the cata- 

 logue of Osten Sacken's the whole of the two continents would 

 have been covered. There are reasons, however, for not doing this. 

 In the first place Osten Sacken's catalogue of 1878 included the 

 species described up to that time from the West Indies and Mexico. 

 At this time, the writers of the Diptera volumes of the Biologia 

 Centrali- Americana, Williston, Osten Sacken and v. d. Wulp have 

 furnished lists of all the species of Mexico and Central America. 

 Moreover, in the present state of the science, nothing more than a 

 recataloguing of these species would have been possible. St. Vin- 

 cent is included not only because it is virtually an integral part of 

 South America, but also because a great deal has been written 

 concerning its fauna since the works mentioned were published. 

 Thus it will be seen that with the catalogue of 1878, the Biologia 

 Centrali-Americana, and the present work, the American continents 

 will be covered. 



The system of classification and arrangement of the families is a 

 combination of two. For the Brachycera Brauer has been followed, 

 save in the one respect of admitting the family Coenomyidse ; and 

 for the Nemocera the system suggested by Osten Sacken in the 

 Entomologist's Monthly Magazine for May, 1891, pp. 35-39, has 

 been adopted. In the present chaotic state of the classification of 

 the Diptera, to accept what appears to be best from various sources, 

 seems a defensible procedure. 



Notwithstanding recent activity in the recognizing of the species 

 described by Walker, I have invariably placed the names applied 

 by that writer, excepting those that have been recognized, at the 

 end of the families to which they are supposed to belong. Although 



TRANS. AM. KNT. SOU. XXVI. JUNE, 1900. 



