especially when the colouring is of at all a thick appearance ; thus 

 cynthia, belonging to this (the aiirinia) group, is confined to the 

 Alps of Central Europe, and romauoci, belonging to the ci>ixia- 

 group, has been found in some of the ranges of northern Mongolia, 

 both east and west, as well as in Central Thibet. Its range is there- 

 fore much wider than that of cijnthia, and it will be necessary to 

 refer to it again. It may be added that iduna from the Altai is 

 much whiter than the same species from polar regions. The distri- 

 bution of the very primitive inerope and the probable method of 

 descent of aurinia from this species have already been spoken of. 

 The extreme variability of aKvinia and the extent of its southward 

 progress both point to its comparatively modern origin, while there 

 can be practically no doubt that desfOntainii, the only species of this 

 group which extends into Africa, has been directly derived, through 

 its var. hirtira, from the Spanish form, var. iherica, of aurinia, 

 though there is no difficulty in distinguishing the two species. The 

 North American species taylnri, acastux, aiiicia, eiUtha, chalcedon and 

 cooperi (perdiccas), as well as other forms probably referable to one 

 or other of these species, extending between them from Vancouver 

 to New York, though mostly inhabiting the Eastern States, all 

 belong to this group, and when this region is more thoroughly 

 explored, it is probable that others will be discovered. A further 

 line of evolution from this group has arisen in the nearctic region, 

 in the form of phaethon and possibly other species closely related to 

 it, but I have no doubt that they have travelled too far from their 

 ancestry to be included in the genus and that their removal from it 

 was entirely correct.* These facts seem to point to the New World 

 as the special scene of the development of the «»;•/» /a-group, 

 though there is at present one known species, ci/nthia, confined to 

 Europe, and another, desfontainii, to Southern Spain and North- 

 West Africa, t and the very restricted range of these species makes it 

 appear likely that there may also be some yet undiscovered among 

 the mountain ranges, or perhaps the lower levels, of the unexplored 

 parts of Asia. 



The fact that there are two high mountain species in the athalia- 

 group, both of which are common to Europe and Asia, while there 



* The genus Phyciodes, which extends into Central and even South 

 America, and which is by most writers mixed up with Melitcea, even to the 

 inclusion of such obviously Melit^eid species as c>/neus and fulvia, may possibly, 

 as hinted by such species as theona, be derived from the aurinia-group of this 

 genus ; to me however it seems far more probable that its origin is directly 

 Brenthid ; the whole pattern of the underside, and usually of the upperside also, 

 points in this direction. It is easy to lay too much stress on the importance of 

 wing markings, but easier still to lay too little. The question depends less on 

 superficial resemblance than on essential identity of derivation. 



t It has been asserted that this species also occurs in Asia Minor, in which 

 case it must there be a derivative of var. orientaliit. If it does so occur it would 

 not be a unique instance of the disconnected appearance of a species in these 

 two widely-separated localities. Zegris eupheme is another case in point. 



