r 



The gmus PhpUolahis O. S. (Dipt, Tipnl). 375 



of speciniens of tlie Californian P. clavujer, waifs of my North Ame- 

 rican collcctions, tlic bulk of wliicli rciuained in the United States. 

 These specimens enabled nie to compare the two spccies in tlieir 

 generic characters, and to publish the result. 



The most obvious diiference betvvecn the spccies consists in the 

 course of the second vein and its surroundings. In coniparing tlie 

 generic description in the Western Diptera, p. 202 — 203, witli the spe- 

 cimens of macrm^a before me, I find everything to agree, cxcept the 

 follovving characters: 



Claviger (1. c. p. 202, lines 12 — 13 from bottom) „first sul)mar- 

 ginal cell about half as long as the second". 



Macrura has the first subm. c. a little s horter than the 

 second. 



Claviger (1. c. line 12) „its slightly arcuated petiole occupying 

 the length of the other half" (of the fii'st subm. c). 



Macrura has the same petiole short, not occupying the length 

 of the other half of the first subm. c. 



The praefurca in macrura has a more distinct curvature at the 

 base and is comparatively shorter than that of claviger; but it is 

 longer (in macrura) than the petiole of the first subm. cell (a little 

 longer in the cf, twice as long in the Q specimen). The praefurca 

 of claviger is, in both sexes, about as long as the petiole of the 

 first subm. cell. 



To make the difference clearer, I shall describe it in other 

 words: „In macrura the fork of the second vein is considerably 

 longer than one half of the length of the Avholevein; the proximal 

 end of this fork is at a considerable distance proximad of the 

 tip of the first vein, and almost opposite the tip of the auxiiiary 

 vein. In claviger the fork of the 2'i- v. is about one third the 

 length of the whole vein; the proximal end of the fork is but very 

 little proximad of the tip of the first vein. 



In rcspect of this difference betvveen the two species, Bergroth 

 very happily suggested, that the Omission of the words: „first 

 subm. c. about half as long as the second, its petiole occupying the 

 length of the other half" in my generic description, would make that 

 portion of the description applicable to both species. 



In my generic description (West. Dipt. p. 203, line 24 from top) 

 the Word at, would be better replaced by near, bccause, as I per- 

 ceive now, the great crossvein in both species is not quite constant 

 in its Position with regard to the bifurcation of the posterior branch 

 of the fourth vein. 



The wing of macrura, especially in the 9. is distinetly broader 

 than that of clai<iqcr. 



