28 GROTE — SPECIALIZATIONS OF LEPIDOPTEROUS WING. [Jan. 21, 



the Parnassiinae, the Riodini-Lycsenidse, as well as the Saturniades 

 among the moths, the "brush-footed " butterflies (Nymphalidae of 

 Scudder and Comstock) as well as the Nemeobiidse have no share 

 and are ho7's de concurs. 



We now come to the direction of the suppression of the media. 

 Herein the Pierid^ lag behind the Nymphalidae {in sensu mihi') 

 with one remarkable exception in the position of vein ivi, the upper 

 branch of the media, which ascends the radius (iiis) to a point beyond 

 the cell, a character repeated only on the hind wings of Nemeo- 

 bius. In all the ''brush-footed" butterflies this vein never leaves 

 the cross-vein at the extreme upper corner of the median cell. 

 Though the latter open and the disappearance of the media by the 

 distribution of its branches between radius and cubitus become 

 complete, still vein ivi never fuses directly with the radius. Did 

 it do so its passage to a point beyond the cell in the process of 

 specialization might be logically expected to follow. What power 

 is it which keeps this vein apart, even in Nymphalis and Potamis, 

 where, in the latter especially, the approximation is carried out so 

 completely? Undoubtedly all these retained and abandoned posi- 

 tions for the veins indicate the action of the dynamical force which 

 fits the wing for variations in the mode of flight. The field observa- 

 tions which are compared with the structure of the wings are as yet 

 scanty in the extreme. I have only brought the opening of the cell 

 and the radial position of iv., into a probable relation with a lofty 

 and sailing flight, a tree life like that led by Potamis iris or Philo- 

 samia cynthia. The passage of ivi along iiig does not seem to help 

 the wing to extended flights. We find it again in the moths, in 

 the Smerinthinae and Citheroniadae. The bunching of the two 

 upper branches of the media near the radius at this point seems, on 

 the other hand, to strengthen the primaries. As these veins are retired 

 from the radius and retain their original generalized position on the 

 cross-vein, closing the cell, so does a more modest terrestrial habit 

 of flight seem to prevail ; so that it seems probable that the Lepi- 

 doptera were not originally high flyers, and that those which now 

 disport among the tree tops are the latest arrivals on their respective 

 and differing lines of phylogenetic descent. 



To return to our immediate subject, the comparison of the special- 

 izations of the Pieridas and Nymphalidae proper. So far as the sup- 

 pression of the media is concerned, the advantage of the Nympha- 

 lidae is quite clear when the most specialized forms are compared, but 



