Prof. Milcs (jenus Paracrocera (Cyrthlae) etc. 325 



((jlobidus Panz., ohsoleia v. d. W., from Wisconsin etc.), no sccond 

 vein at allJ) 



The resiilt of niy research tlius far shovvs that tlie majority 

 of Acrocerae havc the second vein coinplcte, and that, in a mino- 

 rity of cases, it is entirely wanting; but some rare cases occnpy an 

 interniediate position, when the sccond vein is represented by a 

 stump, eithcr at tlie distal or at tlio proximal end. Whether such 

 stumps belong to the specific characters, or are merely casnal 

 aberrations in Single speciniens, is slill a qnestion. Tho luimber of 

 rocorded cases is, as far as I know, oiily tliree: Meigen's specimen 

 of nigrofemorata. and Loew's male and feniale speciniens of bima- 

 cidata (it is not statcd, at any rate, thatLoew had any more than 

 these). And three is too small a number for jnstifying a final con- 

 clusion. But even this small number is sufficicnt to provc that the 

 total disappearance of the second vein is not a consequence of its 

 coalescence with the first. but of its obl Iteration, We can 

 reach the same result without being led to it by the lesson of the 

 stumps. ßy comparing a specimen of glolndiis with another of tri- 

 fjramma., which I have bofore nie, I can easily porceive that the 

 coalescence of the first vein with the costa takes place exactly in 

 the same way in botli species, although in glohulus the second vein 

 is obliterated, while it is present in trigramma. If its disappearance 

 in glohulus had been caused by its coalescence with the first 

 vein, the chitinons structurc of this coalescence along the costa would 

 have shown some difference bet\yeen botli species; but that is not 

 the case. The legitimate inference from this Observation is, that the 

 obliteration of the second vein, in Acrocera., is not a deep-seated 

 character at all, and is not an index of a corresponding change in 

 the rest of the Organisation. And this is what Dr. Griffini terscly 

 and happily expressed in a Single sentence: 'non corrispondcndo alF 

 unico caratterc sudetto' (that is, the character adduccd by Mik, the 



^) A. horealis Zett. and laeta Gerst. probnbly belong here, but 

 the Statements are not qiiite distinct, Gerstaecker says about laeta 

 (p. 352): „Venatioii like that of orhiculus." This must be a lapsus 

 calami for glohulus, because Gerstaecker considers orbiculus F. 

 (9) as a synonym of glohidus Panz. of. Sc hin er (Fn. I. p. 73, 

 foot-note) says: „The olcler nanie is properly orhicxdus Fab. Ent. Syst. 

 1794. But as bofh monographers, Erichson and Gerstaecker, liave 

 rctained Panzer's iiame, I prefer to follow tliem." This is not quite 

 correct, because Ericlison considered orhicidus T. (Q) as a separate 

 species, and it was Gerstaecker \\\\o united them uiider the younger 

 iiame globidus Panzer cf (1803). Why he did so, is not quite clear, 

 and Griffini niay be rig-ht after all in preferring orhicidus. 



