74 THE CANADIAN ENTOMOLOGIST. 



The course of development, as well as the general appearance of the 

 imagoes of all broods were practically alike. In its life-history, the 

 species differs somewhat from our eastern forms in moulting only five 

 times, and all the individuals of a whole generation passing their trans- 

 formations quite regular in about eight weeks, from the deposition of eggs 



to perfect insects. The last larval stage has a prolonged duration and the 

 very restless larvse at this period are inclined to attack and destroy each 

 other. The very active and erotic males of this and other species of our 

 N. A. Arctians manifest a decided inclination for uniformity of colour, 

 gradually eliminating the probably original black to finally uniform white ; 

 the conservative females apparently striving to retain and extend their 

 dark colour. More constant forms like virgo, even show in the male sex 

 a varying but decided paleness of the red colour of hind wings. In 

 closely related European and Asiatic genera the wings of the sluggish, 

 retrograde females are rudimentary. (Ocnogyna; Tancrea pardalina ; 

 R hyp aria leopardina.) 



The tendency of the males to diffuse the light colour from the 

 probably original sources — the veins*— ^and its transmission by the male 

 parent seems to be constantly counteracted by the conservatism conveyed 

 by the female parent. The vacillating, but still aimed variability of some 

 of our more vital species, perhaps finds here its principal solution. In the 

 much-disputed nais group, for instance, the 'females of the four distinct 

 species (all probably originally deriving from nais, but now distinct) are 

 recognized and separated from each other without the slightest difHiculty, 

 while the males, striving finally towards uniform and light coloration, are 

 naturally bound to create resembling forms, merely by the two antagonis- 

 tic principles inherited from the male and female parents. To consider 

 these species as lingering in a status nascens might as well apply to all 

 variable forms. 



Stimulated by high temperature, it seems with the males o^ proxima 

 that the black colour is gradually eliminatecf ; the process generally begins 

 with the area from 2nd to 4th transverse bands, which, widening in excess, 

 leave (as far as the experiments reach) only two black irregular costal 

 marks and a geminate dot at interior margin of middle area, besides 

 traces of the black colour near base ; the dorsal black maculation of 

 abdomen is almost entirely superseded by red and the black of terminal 



*Dr. Chr. Schroeder, Zeitschrift f. Entom., July, 1904, p. 257. 



