64 DIPTERA OF NORTH AMERICA. [PART III. 



abundantly represented in America and likewise belongs to this 

 division. A whole series of related genera, peculiar to America, 

 may be classed with Richardia : like the latter, they are all 

 distinguished by armed femora. 



This is the reason why, in a former publication, I separated 

 the whole second division of the Ortalina in two groups, the one 

 with unarmed, the other with armed femora ; the first I called 

 Ulidina, the second Richardina ; and in the Berlin Entom. Zeit- 

 schrift, Vol. XI, I described the American Ulidina which, at 

 the time, were known to me. Now, however, that I have become 

 acquainted with a larger number of forms belonging in this 

 division, I incline to think that its separation in the groups 

 Ulidina and Richardina becomes more natural, if, as a distin- 

 guishing character of these groups, we assume, not the armed or 

 unarmed femora, but the shape of the anal cell. All the genera 

 having the posterior angle of the anal cell more or less pointed 

 belong to the Ulidina; those genera, on the contrary, where this 

 is not the case are to be placed with the Richardina. This 

 modification does not much alter the distribution of the genera 

 among these two groups, as all the genera with armed femora, at 

 present kuown, will, in the new distribution, be likewise referred 

 to the Richardina. Among the genera which, in the above- 

 quoted publication, I placed with the Ulidina, Epiplatea alone 

 will have to be transferred among the Richardina. Among the 

 genera of Richardina, enumerated below, Steneretma, according 

 to the former mode of subdivision, would have belonged to the 

 Ulidina, and thus would not have been placed near Idiotyjja, 

 which is closely allied to it. With the former mode of distribu- 

 tion, the position of the new genus Coniceps, based upon a North 

 American species, would have been a somewhat doubtful one, as 

 the under side of its hind femora bears a few stronger hairs, but 

 can hardly be called armed. 



First Section: Ulidina. 



The five genera of Ulidina represented in Europe, and 

 enumerated in the preceding paragraph, are not confined to this 

 part of the world. The European Seoptera vibrans also occurs 

 in the adjoining provinces of Asia, and is represented in America 

 by a species most closely resembling it. European species of 



