ORTALIDSE — SYSTEMATIC DISTRIBUTION. 61 



Pterocalla ocellata, so that this outline must be considered as 

 the principal diagnostic character of this genus. 



Among the numerous undescribed Pterocallina, which I have 

 seen, I know of no one which may be placed in the genus Piero- 

 calla, although several of them agree with the species of this 

 genus in some one point pertaining to the venation. But none 

 of those species has the wings of that peculiar shape which 

 characterizes Pterocalla ; on the contrary, the outline of the 

 wings of all these species does not, in any marked degree, differ 

 from that of the ordinary Ortalidse. Like the species enumerated 

 above, they have this peculiarity, that each species, although 

 agreeing with the others in the characters belonging to the 

 group, at the same time shows such important plastic differences, 

 that the establishment of a series of new genera becomes indis- 

 pensable. I regret not to be able to enter here into the detail 

 of this subject, as, without plates, it is impossible to define those 

 genera sufficiently. Thus much only will I mention, that among 

 them there is a species which has the posterior angle of the anal 

 cell rounded. The generic distribution of the North American 

 species, which will be described below, does not, fortunately, 

 require these South American forms to be taken into considera- 

 tion. 



Among the North American Pterocallina, Ortalis vau Say 

 is the nearest to Myennis fasciata Fab. The venation, however, 

 is different enough to prevent us from placing them in the same 

 genus. The two crossveins in 0. vau are less approximated, and 

 the anterior end of the posterior one is further from the basis of the 

 wing than the posterior end, while in Myennis fasciata the con- 

 trary is the case, so that the posterior crossvein of this species has 

 a different position. Moreover, the first segment of the ovipositor 

 of the female of Ortalis vau has not the conically attenuated 

 shape which it has in Myennis fasciata apd in many Trypetina ; 

 it is broader, somewhat attenuated from its middle only, like the 

 ovipositor of the majority of the Ortalidse. I consider, therefore, 

 Ortalis vau as the type of a new genus, which I call Stictoce- 



PHALA. 



To Stictocephala vau must be added a second North American 

 species, which I received from Baron Osten Sacken, under the 

 name of Tephritis corticalis Fitch in litt., and which will be de- 

 scribed by me under the same name. The venation resembles 



