Mr. Edward Doubleday's Remarks on the Genus Arg-ynnis. 481 



merely a faint line extending from the disco-cellular to the base, evidently not 

 tubular. 



Thns in Castnia, where it branches about the middle of the discoidal cell, the 

 upper branch is often almost atrophied ; in Heleona mWitaris it is in this state 

 throughout its whole course ; in Urania and Leiocarnpa its course is indicated 

 by a line, which shows no symptoms of being tubular, and which in the latter 

 genus does not reach the base. One step more and it has vanished from the 

 wing, though sometimes in certain lights a faint trace of it may with difficulty 

 be detected. A close examination of the wing will always show a partially atro- 

 phied disco-cellular, connecting these nervules of the discoidal with either the 

 subcostal or the median nervures, even where one of them has been described 

 as quite free. 



We thus see the discoidal nervure becoming gradually atrophied until only 

 its nervules remain ; and as air must in some way penetrate into them, they 

 are, when the parent trunk has vanished, attached to the nervure immediately 

 above or below them, or to both. 



Admitting the correctness of the above views, we have in the Rhopalocera a 

 median nervure with constantly three nervules, above which are the two dis- 

 coidal nervules, then the subcostal nervure generally offering five nervules, 

 but sometimes only three. In the Suspensi the number of these nervules is 

 almost invariably five, but in the Succincti it is more variable, especially in 

 the Eryc'midce. Not unfrequently these nervules anastomose with the costal, 

 as in some species of Pap'dio and Danaus and in Hecalene Clytemnestra, &c. 

 Leptocercus presents an almost solitary instance of a bifurcation of one of these 

 nervules ; but perhaps the more correct view of this would be to consider that 

 two nervules coalesce at their base in a manner analogous to the union of the 

 costal nervure with the first subcostal nervule in some species of Danaus. 



The genus Argynnis of Godart always offers five subcostal nervules, never, 

 I believe, anastomosing with the costal nervure. - ■ 



If we remove from it three species, -^rg. Alcandra, Aceste and Lucina, and 

 add to it some of the Cethosice, it is, as I have already said, a most natural 

 group. Perhaps a fourth species, Arg. Metea, ought to be excluded also, but 

 I only know it from Stoll's figure, which leads me to believe it to be a Dia- 

 dema. 



3 r2 



