234 DIPTERA OF NORTH AMERICA. [PART II. 



them, it is impossible to determine which of the competing species he 

 had before him. Wiedemann's description of the same species affords 

 no light ; he does not state the sex of the described specimen, but it 

 is evident from his statements about the color of the feet, that it 

 was a male. If this male specimen were still in his collection, 

 which unfortunately is not the case, the species, which he obtained 

 from Say as P. femoratus, could be easily determined. Considering 

 the great similarity of the species belonging to this group, this 

 would by far not settle the question, whether Say had described as 

 P. femoratus one of these species, or whether he had mixed it up 

 with others. I regret to say that in Wiedemann's collection there 

 are, under the name of P. femoratus, only two females, which, judg- 

 ing by the pins, came from Say ; one of these females I believe to be 

 P. scobinator, the other P. caudatulus; considering, however, the 

 great difficulties attending the distinction of the females of this 

 group, I cannot render a positive decision. Thus P. femoratus of 

 Say, as a species, will have to remain unnoticed, as it cannot be 

 determined with certainty. 



6. pallens Wied. This species is easily recognizable as one of those in 



my possession. Wiedemann furnishes only the description of the 

 male ; in the following I communicate the description of both sexes. 



7. macula Wied. This is a species entirely unknown to me, and remark- 



able by the unusual picture of the wings. 



8. diffusus Wied. In Wiedemann's collection there are two totally dif- 



ferent males under this name. That which bears the etiquette is 

 remarkable by the more diluted, as if diffused, picture of the wiugs, 

 so that it may be supposed that Wiedemann had this specimen par- 

 ticularly or exclusively in view when he described and named this 

 species. I accept this specimen without hesitation as the genuine 

 P. diffusus Wied. Upon its etiquette the evidently incorrect state- 

 ment of its patria, " Savannah," is crossed out and changed by 

 Wiedemann himself into "Rio Janeiro." The other male, placed 

 alongside of the etiquette, is that of P. jucundus, common in Cuba 

 as well as in Brazil. In Winthem's collection a male and a female 

 named P. diffusus are found. The male is the same as the typical 

 male in Wiedemann's collection. The female, which is alongside 

 of it, agrees very well in many characters with P. diffusus ^ » shows 

 however a few differences, such as should not be expected from a 

 female of P. diffusus. For the outlines of the picture on the wings 

 are not only better defined, but the blackening on the fore margin 

 begins only beyond the end of the first longitudinal vein, while in 

 the male it begins already before it ; besides, the bristles on the fore 

 and middle tibia? are very much longer than in the male of P. dif- 

 fusus. I should not take this female for that of P. diffusus, if I had 

 not received a number of precisely similar specimens from Brazil, 

 as being the females of a male belonging to P. diffusus. For these 



