THE CANADIAN ENTOMOLOGIST. 125 



having the same general characteristics, but exhibiting definite, transmit- 

 table structural differences from all other forms of life — a definition which 

 does not touch the construction of genera. 



From each species are given off from time to time individuals in 

 greater or less numbers diff'ering from the parent form and from any other 

 species ; these forms sometimes exhibit transmittable differences, some- 

 times not transmittable, but in nearly e\ery case are connected by almost 

 imperceptible gradations or known circumstances of origin with the form 

 from which they sprung, the extremes of variation being sometimes so 

 great that in the absence of knowledge of intergrades or attendant cir- 

 cumstances, they would readily be declared distinct species. 



In the case of those species where the departures from the normal 

 form appear at all seasons and in all broods without restriction to locality 

 and with satisfactory intergrades, it seems to me that a good end would be 

 served by ceasing to consider them " varieties," but merely terming them 

 " variations " and designating the extremes of variation by letter, as 

 Variation A, or by name, if the practice be more agreeable, as in the case 

 of Cat oca la sciriti/latis, a name given to an extreme variation of C. innu- 

 bens. which occurs in all broods without restriction to localitv and with 

 perfectly satisfactory intergrades, which would thus become Variation 

 scintillaiis- a name that would at once express its relation to C. iumibens. 



Thus relieved of an embarrassing number of forms whose title to the 

 dignity of varieties is, to say the least, dubious, we might classify actual 

 varieties as follows : 



Seasonal — Where a certain variation of form appears only or mainly in 

 certain broods of many brooded species, disappearing in following 

 broods only to reappear in the succeeding year at its proper 

 season, as Papilio Walshii. 



Climatic — Where varieties occupy considerable habitats, often to all 

 appearance distinct species when viewed at the extremes, but hav- 

 ing common ground where intergrades occur or either form is 

 produced indiscriminately, as in the varieties of ^. alope. 



Dimorphic — Where well marked varieties do not thoroughly intergrade, 

 but appear in all broods and are produced indiscriminately regard- 

 less of sex, as in Grapta comma. 



Occasional — When aberrant forms are produced in both sexes rarely and 

 at irregular intervals, as Papilio Calvcrleyii. 



