THE CANADIAN ENTOMOLOGIST. 131 



unique in color, being greenish-yellow, but is not otherwise variant from 

 usual form. 



Another family consisting of twenty-five ^ s and thirteen ^ s, from 

 eggs laid by one female, scarcely, if at all, surpasses the averages of 

 the caught material as to expanse. The twenty-five ^ s show an 

 average of only 50^ mm., while the caught males average 51 1-5 mm. 

 The thirteen $s average slightly larger than the caught females, 53 mm. 

 against 523^ mm. As to pattern, the females present a rather more 

 perfected type than the out-door average, but the males are scarcely 

 equal to the natural average. 



The relation found in these two bred families between the numerical 

 proportion of the sexes and the degree of type development, lends some 

 support to the hypothesis that favorable conditions during larval growth 

 tend to a greater production of females, while less favorable conditions 

 produce an increased outcome of males. The proportion of males to 

 females in these two broods is in great contrast. The brood which shows 

 such improved averages contains slightly more than an even share of 

 females ; and the family averaging scarcely up to nature's mean level 

 contains a large overplus of males. 



Additional to the direct evidence derived from inspection of the 

 butterfly, there are several circumstances which add somewhat to the 

 probability that Elis is a good species. Of some little weight, perhaps, 

 is the argument from geographical distribution, that so far as known there 

 is a great gap of country between the district of the form Elis, and the 

 territory in whicli dwells Meadii proper. Should later discovery be made 

 of Elis considerably further south, or of Meadii much more to the north 

 than at present known, the probability of their distinctness would be some- 

 what lessened. Another and better argument is the inference from 

 relative altitude. Meadii is normally an alpine butterfly, Elis is sub- 

 alpine. All accounts agree that Meadii lives above timber, though like 

 other alpine habitants, it may in peculiar circumstances make excursions 

 to a lower level. Just such an incident may have originated Elis. One 

 needs not an india-rubber imagination to suppose that somewhere in its 

 mountain line of territory, under specially favoring conditions, Meadii 

 may have established a colony below timber line. That accomplished, 

 and the feeble colony proving able to maintain itself in the changed con- 

 ditions, all the elements of the case would combine to speedily separate 

 the new from the old, in kind. Perhaps hardly in any other way could 



