1898.] GROTE — SPECIALIZATIONS OF LEPIDOPTEROUS WING. 37 



become very short indeed in A. ausonides. A. belemia would be 

 the most generah'zed form, since \\\^ has not, or hardly, passed the 

 cross-vein. In both belia and ausonides this halting place has been 

 passed by. But in Tetracharis (n. g.) cethura Feld., sp., we have 

 a four-branched Euchloe ; one which represents an intermediate 

 stage between the five-branched Euchloe and the three-branched 

 Pontia. Tetracharis may be represented also by other spe- 

 cies, since I have not been able to examine all the. forms of the 

 Anthocharini. 



This survey of the Pierinae has shown us that the Anthocharini 

 represent the most generalized forms apparently in the holarctic 

 fauna, and that they are probably the survivors, not on the direct 

 line, of a former five-branched condition of the family. There 

 remains one more five-branched form to examine : Leptidia 

 (Leucophasia), but this presents so strange a neurational pattern, 

 that it must have come into its present company by a vastly different 

 route. Of its peculiar type it may be a specialized form, although, 

 in comparison with the Pierin^e, it seems generalized. Its white 

 color has come to it, I think, subsequently ; as to its origin — 

 unde et quomodo — I have no idea which is not imaginary. 



To touch finally another aspect of our subject — a study of the 

 dynamics of the butterfly wing has been somewhat neglected. From 

 the details of the changes in the position of the veins, it may be 

 concluded that the movements have a mechanical cause. Since 

 this inquiry belongs to a department of direct observation upon 

 which we can obtain absolute knowledge, without employing recon- 

 structive methods, it may be painfully followed up, in field and 

 cabinet, until the subject becomes clear. The butterflies certainly 

 owe a part of their attractiveness to the fact of their seasonal 

 appearance. They recur at a certain niveau in the biological 

 circle, thus relieving the mind through their plain testimony from 

 doubting that the principle of existence is succession. 



