CHIONOBAS 1. 



to whose zeal and skill lepidopterists owe the discovery of several new species 

 of Californian butterflies, and a better acquaintance with many i-are ones. Mr. 

 Behrens wrote, 2Gth June, 1873 : " I caught seven of the large Chionohas in 

 Mendocino County. It seems to be a very local species, and confined to high 

 ridges in the depth of the red-wood forest. They would alight on a hot, sandy 

 spot, or on a fallen tree, or on the fresh leaves of young oak trees, always in the 

 heat of the sun. Fallen trees and dense thicket make the chase for them difficult. 

 They are very vigilant and shy, but will return to a spot they have once visited, 

 though for a short hour of the day only, either earlier or later, according to the 

 state of the atmosphere and wind, and when tired from their usual high, rapid 

 flight. Water and moisture do not seem to attract them. They should be 

 looked for in the month of May, as soon after they become shattere<l. It is 

 almost impossible to obtain a perfect specimen later." 



Iduna is one of the lai'gest known species of Chionohas, rather surpassing even 

 G'ujas, Butler. These two form a sub-group, separated hj no wide interval from 

 Necadensis, Felder, and Califonilca, Boisduval. The several species of this 

 genus are mostly alpine or boreal, Iduna and Gi.gas apparently being the excep- 

 tions, the former living upon ridges of moderate elevation, and Giqas being 

 taken at quite low levels. Three other species, Chri/xiis, Uhlerl, and Semldea, 

 inhabit tlie mountains of Colorado, and of these Cliryxus is taken in California 

 and at Hudson's Bay [Calais, Scudder, proving to be the female of this species), 

 and Semidea abundantly on the sunnnits of the White Mountains, New Hamp- 

 shire. Over the most northern portions of the Continent still other species of 

 Chionohas are found, and of these all seem to inhabit corresponding parts of 

 Europe and Asia. 



Iduna may readily be distinguished from Gigas. It has less curvature of 

 costal margin of primaries, and much less rounded hind margin ; the same wing is 

 also more produced, or pointed apically ; tlie ocelli are diflereutly arranged, those 

 of Iduna being set in a straight line, of Gigas irregularly, the small ocellus of 

 first median interspace lying outside a straight line connecting the larger. This 

 peculiarity is observable in the two females in my own collection, and also in the 

 unique male in British Museum collection, as mentioned by Mr. Butler, who first 

 directed my attention to this peculiarity of the species. On the under side, the 

 outer edge of the discal band in Gigas is scolloped from margin to margin ; in 

 Iduna it is not scolloped, but irregular. These differences may be seen by refer- 

 ence to the Plate, and they are constant in all the individuals of either species 

 at present known in collections. 



