10 D1PTERA OF NORTH AMERICA. [PART in. 



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 Lonchsea, cells 

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

 reasons induce me to exclude Lonchsea from among the Ortalidse. 

 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 Lonchsea 

 and the genera of Ortalidse, 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 Lonchsea 

 and the genera of Ortalidse 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 Lonchsea from the Ortalidse 

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

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

 Pallopteridse 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 Lonchsea as the typical genus of a separate, small 

 family, intermediate between the Pallopteridse and the Ortalidse, 

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

 fore, be left for future investigation. 



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

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

 applied to the former. 



Summary of the European Ortalidse. 



From what precedes may be deduced the following list of 

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

 family of Ortalidse: all the species of Ortalis, in Meigeu'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, Trypetafasciata. 



