ORTALID^E — SYSTEMATIC DISTRIBUTION. 33 



Adapsilia shows a striking character, distinguishing it from 

 all the others, in the absence of ocelli and the not flattened ovi- 

 positor. 



Scatophaga fasciata with its broad and low head, the circular 

 shape of its third antennal joint, and the considerable distance 

 intervening between the end of the auxiliary vein and that of the 

 first longitudinal, has a general appearance which differs from 

 the four other types so much that for a long time the close re- 

 lationship of this species with the others was, for this reason, 

 misunderstood. 



Ortalis, Platystoma, and Cephalia differ in a very marked 

 way in the mode of insertion of the bristles upon the pleurae. 



Ortalis has a strong bristle immediately above the basis of the 

 fore coxae ; this bristle is not extant in Cephalia and Platystoma. 



Cephalia has above the middle coxae, but below the longitudi- 

 nal suture of the pleurae, a strong bristle, which is also present 

 in Ortalis, but entirely wanting in Platystoma. If, for the sake 

 of brevity, I call the first prothoracic, the second mesothoracic 

 bristle, the difference between these three genera will be as fol- 

 lows : Ortalis has a prothoracic and a mesothoracic bristle ; 

 Cephalia has the mesothoracic bristle only ; in Platystoma both 

 are wanting. 



First Section: Pyrgotina. 



I borrow the name of this group from the genus Pyrgota Wied., 

 to which Adapsilia is most closely related. Both genera agree 

 in the absence of ocelli, in the projecting front, the prolonged 

 second antennal joint, the retreating face, the comparatively but 

 little developed clypeus, the prolongation of the first abdominal 

 segment in both sexes, and the contraction of the following seg- 

 ments in the female, as well as in the capsule-shaped structure 

 of the first joint of the ovipositor, and in several other sub- 

 ordinate characters. 



The principal difference between these genera consists in the 

 structure of the antennal foveae, which, in Adapsilia, run down 

 in a parallel direction as far as the edge of the mouth, and are 

 separated by a straight ridge, while in Pyrgota they end at some 

 distance from the edge of the mouth, and are more or less 

 coalescent. 



The South -African genus, Hypotyphla, founded by me, agrees 

 3 



