93 



no ? . The S is like Oleracca hyemalis, but is duller, yellower, 

 and has longer hind wings with much longer discoidal cells T In 

 originally describing this form Mr. Scudder had before him my 

 Slave Lake examples, and when he says that Frigida " is more 

 heavily marked than the extremes of Oleracca^' he included in this 

 last individuals as extreme as var. Borcalis. Frigida is another 

 island form brought over from the main land, beyond doubt single- 

 brooded, and seems to have acquired some peculiarities of its own. 



The summer brood, cestivaoi Oleracea,\s often of larger size of 

 wings, and the wings are thinner, and purer white on upper side 

 than in hyemalis. So the base is less obscured, the costa, apex 

 and hind margin not at all. On under side it is either white or 

 delicate yellow ; the veins of both wings are but scantily edged 

 with brown scales, and often not at all over considerable areas. 

 The females have the basal and apical areas pale gray, and not infre- 

 quently there is a trace of the spot of Napi on upper median inter- 

 space. Sometimes also a trace of the second spot (in sub-median 

 interspace), and of the gray bordering to inner margin of prima- 

 ries. The veins beneath are rather more edged with brown scales 

 than in the male. The shoulders of hind wings are of a very pale 

 yellow (in hyemalis decidedly yellow or saffron), and often there 

 is no color at all. There is some difference in the shape of the 

 wings in each sex, some individuals having the apex of primaries 

 more rounded than others, and secondaries more narrow. 



I have found that eggs laid by females of hyemalis in confine- 

 ment produce the same season butterflies, aestiva, and that 

 eggs laid by (estiva produce the following spring hyemalis. But 

 in one instance from eggs of cestiva, laid in the Catskills, there 

 emerged, at Coalburgh, the io\\o\\{r\gM.3.xc:]\,tiuo bntterjlies, one of 

 which was as true (.estiva asthepare7it, the other hyemalis. 



The summer form is identical with Casta, Kirby, described as 

 having the wings white ; black scales sprinkled over costa of 

 primaries ; secondaries beneath, with a few scattered black scales 

 along the nervures. The female Oleracea of Harris, in Agassiz' 

 Lake Superior, is this (jestiva, as before mentioned. 



Boisduval also described P. Cruciferarwn,S'^ec. Gen., 51^, $. 

 A little smaller than Raixe. " Upper side of the wings almost the 

 same white, immaculate ; primaries having only the anterior third 

 of the costa and a part of the base dusted gray. Under side of 

 secondaries and summit of primaries washed with very pale 

 sulphur-yellow ; secondaries have the origin of costa of a light 

 yellow-orange. It replaces onr Ratxe in the middle U. S." As 

 Rap(e was then (1836) unknown in N. A., this could only be 

 Oleracea (estiva. That is, it is the summer generation of what 

 Boisduval had before described as Oleracea. 



Venosa, therefore, represents Napi (winter form) at the ex- 

 treme west, and Oleracea hyemalis represents the same Napi to 

 the eastward, in almost all known localities. Specimens from 



