10 DIPTERA OF NORTH AMERICA, [PART III. 



venation of the wings having proved, in so many cases, to be the 

 most trustworthy character for the distinction of the families of 

 diptera, we have to take care not to attach too little importance 

 to the smallness of the posterior basal cells in Lonchaea, cells 

 which, in the Ortalidae, always are of a considerable size. These 

 reasons induce me to exclude Lonchaea from among the Ortalidae. 

 Those entomologists who take the European fauna alone in con- 

 sideration, will, I have no doubt, justify this course, as that 

 fauna does not contain any intermediate forms between Lonchaea 

 and the genera of Ortalidae, but I am not quite as sure of the 

 approbation of those who have a wide acquaintance with the 

 diptera from all parts of the world, because, among the number, 

 forms occur which seem to be intermediate between Lonchaea 

 and the genera of Ortalidae allied to Ulidia, and it is possible 

 that the discovery of a large number of such forms may, at some 

 future time, render the exclusion of Lonchaea from the Ortalidae 

 less plausible than it appears to me now. In the first volume 

 of these monographs, I placed this genus in the family of the 

 Pallopteridae and considered it as the typical genus of a second 

 group in this family. Whether this arrangement, which I for 

 the present retain, is satisfactory, or whether it would not be 

 better to take Lonchaea as the typical genus of a separate, small 

 family, intermediate between the Pallopteridae and the Ortalidae, 

 is beyond the scope of the present discussion, and may, there- 

 fore, be left for future investigation. 



The genus Earomyia is so near Lonchaea, that, with regard 

 to its systematic position, whatever I said of the latter may be 

 applied to the former. 



Summary of the European Ortalidae. 



From what precedes may be deduced the following list of 

 genera and species of European diptera, which I place in the 

 family of Ortalidae: all the species of Ortalis, in Meigen's 

 sense, with the exception of 0. pceciloptera and connexa ; 

 Sciomyza bucephala ; the genera Adapsilia, Dorycera, Teta- 

 nops, Psairoptera, Cephalia, Platystoma, Timia, Ulidia, Chry- 

 somyza, Empyelocera, and, finally, Trypeta fasciata. 



