xlviii 



annually, the first of which is Mat'cia, or the winter form, and the 

 other is the summer form, and a certain proportion of the larvss 

 proceeding from the first hybernate (so far as appears), and all 

 those from the second ; whilst at Coalburgh, W. Virginia, there 

 are four generations annually, the first being Marcia, the second 

 and third Tharos, and the fourth mixed. 



A further communication on the life -history of Phyciodes 

 Tharos, by Mr. W. H. Edwards, in the subsequent number of the 

 ' Canadian Entomologist,' has shown that not only P. Marcia and 

 Tharos, but also P. Phaon, Vesta, and probably also Batesii, are 

 to be regarded as periodical varieties of one variable species, of 

 which Drury remarked, more than a hundred years ago, " Nature 

 forms such a variety of this species that it is difl&cult to set bounds 

 or to know all that belongs to it." The fact that variations in 

 colour and markings correspond in this species with variations 

 in periodicity have led Mr. Edwards to conclude that "When 

 Phaon and Vesta and Tharos were as yet only varieties of one 

 species the sole coloration was similar to that now common to the 

 three. As they gradually became permanent, or, in other words, 

 as these varieties became species, Tharos was giving rise to several 

 sub -varieties, some of them in time to become distinct and well- 

 marked, while the other two, Phaon and Vesta, remained con- 

 stant." Dr. Weismann, commenting on Mr. Edwards' experiments 

 and their results, observes, in a letter to him, " The case seems to 

 me perfectly intelligible : Marcia is the old primary form of the 

 species, and in the glacial period, the only one. Tharos is the 

 secondary form, having arisen in the course of many generations 

 through the gradually working influence of summer heat. In your 

 experiments, cold has caused the summer generation to revert to 

 the primary form. The reverting which occurred was complete 

 m the females, but not in all the males. If so treated the summer 

 brood of Levana will, in many more females than males, revert to 

 the winter form. This sex is more conservative than the male — 

 slower to change." 



An instance of the so-called "mimicry" existing between insects 

 of different orders, and in which a very striking resemblance exists 

 between Vespa orientalis and a species of the dipterous genus 

 Laphria, has been communicated to the Cambridge Philosophical 

 Society (Proceedings, vol. iii., Feb. 1877). The author proposes 

 to confine the term "mimicry" to cases of resemblance between 



