ORTALID^E INTRODUCTION. 3 



The frontal fissure is distinct, but the frontal lunule is not 

 pushed up as far as the front, so as to seem to form a part of. 

 it ; on the contrary, it appears as the upper part of the face. 



Vibrissae, such as they appear in all the genera of Helomyzidae, 

 are not extant. 



The clypeus is always distinct. The palpi are rather broad ; 

 the proboscis more or less stout. 



The metathorax is larger than usual, very much projecting 

 inferiorly and posteriorly. 



The feet short and strong, rather than long and slender ; 

 middle tibiae distinctly spurred ; front and hind tibiae spurless ; 

 the erect bristle extant in several families of the Diptera acalyp- 

 tera on the upper side of the tibiae, near their end, for instance 

 in the Sapromyzidse and Sciomyzidse, does not occur here in any 

 species. 



The abdomen of the male has four segments, the first of 

 which, like the first segment of the female abdomen, is formed 

 of two coalescent segments ; the diminutive fifth segment of the 

 male abdomen forms the small, more or less imbedded hypopy- 

 gium ; the sometimes more filiform, in other instances tape-like, 

 rolled up penis is of an extraordinary length. 



The abdomen of the female consists of five segments ; the 

 sixth, seventh, and eighth segments are converted into a flat- 

 tened, extensile ovipositor, the first joint of which surpasses the 

 two following in breadth very much, and is often colored like 

 the rest of the abdomen ; the slender last joint of the ovipositor 

 ends in a simple point. 



The wings show the complete venation of the Diptera acalyp- 

 tera ; the auxiliary vein is entirely separated from the first 

 longitudinal vein, although it is sometimes rather approximated 

 to it; it ends at a more or less acute angle in the costal vein, 

 without becoming less distinct at its end ; the first longitudinal 

 vein is provided with bristles, at least at its end ; the two pos- 

 terior basal cells are comparatively large. 



2. Species erroneously placed in the genus Ortalis. 



The agreement of all the species placed by Meigen in the 

 genus Ortalis would have been complete if 0. pceciloptera 

 (fulminans M.), connexa, vibrans, and syngenesise did not 

 show differences, which require a special mention. 



0- pceciloptera and connexa differ from the other species in 



