6 DIPTERA OF NORTH AMERICA. [PART III. 



I know of no other European genus which, although still more 

 distant from Ortalis in the direction of Adapsilia, would never- 

 theless be admissible into the family of Orlalidse. 



2. Forms reminding of Ortalis syngenesise. 



If, in our search for forms related to Ortalis, we start from 

 Ortalis syngenesise, distinguished by its four-jointed female abdo- 

 men, the genera Ulidia, Timia and Platystoma at once claim our 

 attention. 



Ulidia, in Meigen's sense, is not a homogeneous genus. Ulidia 

 demandata is too aberrant to remain in it. Together with seve- 

 ral exotic species allied to it, it has to form a separate genus for 

 which Chrysomyza, a name already used by Fallen for Ulidia 

 demandata, may be applied. 



Timia apicalis, described by Meigen, is nothing but an Ulidia, 

 and must be referred to this genus; the differences which appear 

 in Meigen's statements and his figures do not exist in nature. 



Timia erythrocephala, upon which Wiedemann, in the Ana- 

 lecta, has founded the genus Timia, differs from Ulidia only in 

 its extreme glabrousness, its swollen head, much more project- 

 ing beyond the eyes in profile, and perhaps also the somewhat 

 less developed clypeus ; in all the other important characters 

 both genera agree. 



In all the species hitherto placed in the genera Timia and 

 Ulidia, and consequently also in the species of Chrysomyza, the 

 first longitudinal vein is bare. In all other respects, these spe- 

 cies share all the characters common to the species of Ortalis, so 

 that, in my opinion, their position among the Ortalidse cannot 

 well be disputed, unless we separate from this family all the spe- 

 cies the first longitudinal vein of which is bare. Nevertheless, 

 the relationship between the species of Ulidia, Timia, and Chry- 

 somyza to Ortalis syngenesise cannot be considered as unusually 

 close, because they differ from it, not only in the bareness of the 

 first longitudinal vein, but also in the presence of a fifth, very 

 much abbreviated, segment of the female abdomen. 



A genus agreeing with them in the bareness of the first longi- 

 tudinal vein, and most closely related to them, is the genus Em- 

 pyelocera, introduced by me. 



The genus Lonchsea also seems related to Ulidia ; I will, 

 therefore, in the sequel, explain its systematic location. 



The species of Platystoma differ somewhat from Ortalis in the 



