38 DIPTERA OF NORTH AMERICA. [PART IV. 



South America and by Macrochile in amber. Teucholabis, and 

 some allied, and as yet undescribed forms, are well represented 

 in South America and Mexico ; Gnophomyia likewise. 



Geranomyia is represented in Europe by two rare species ; it is 

 common in North America, and still more abundantly represented 

 in South America. Those North American species of Epi- 

 phragma and Rhipidia, which are not represented by analogous 

 forms in Europe, are South American forms. 



Some species, characteristic of North America, as Limnophila 

 (Lasiomastix) macrocera Say, Limnophila tenuipes Say, and 

 some other species with long antennas in the male sex, are repre- 

 sented quite abundantly by analogous forms in amber ; one of 

 them, Limnophila longicornis Loew, seems to be closely allied 

 to L. macrocera Say. 



It would be interesting to push the comparison of the two 

 faunas still farther, and, by taking up the genera singly, to com- 

 pare the North American and the European species, so as to 

 arrive at some results as to analogies or differences in their 

 structure, coloring, or size. Erom want of materials for such a 

 task, my remarks will be very fragmentary. 



In this family, as in most of the other families of Diptera, there 

 is a certain number of species, which are apparently common to 

 Europe and to North America. I say apparently, because with 

 such species one is never sure whether the comparison of a larger 

 number of specimens would not disclose a constant difference. 

 And as every kind of difference, even if constant, does not neces- 

 sarily constitute a specific character, cases of this kind are often 

 doubtful, and their decision more or less arbitrary. 



My opportunities for comparing specimens having been small, 

 it is with such reservations that I have to introduce the. list of 

 identical or analogous species of both continents. 



The following species, as far as ascertained, seem to be common 

 to Europe and to North America : Dicranomyia liberta 0. S., 

 D. longipennis Schum. (syn. D. immemor 0. S.), Rhipidia macu- 

 lata Meig., Symplecta punctipennis Meig., Antocha opalizans 

 O. S. 



The identity of the following species is less certain, their re- 

 semblance, however, very great : Dicranomyia morio Fab. and 

 morioides 0. S., Trochobola annulata Lin. and T. argus Say; 

 Ephelia (an unnamed European species in my collection, perhaps 



