38 
logical condition (bleaching, etc.) more often than not. But it is 
possible to go further than this with mere casual observations. 
Restrictions of underside aberrations. —Casual observations give rise 
to impressions which lead one to examine on one or two different lines. 
First in the crypton. This shows extremely frequently the only 
variation in the specimen as regards the underside, whether in homo¬ 
logous (Lycaenid) or heterologous [Aryynnid (Brenthid)] undersides. 
To take a familiar group, the Lycaenids :—Melanotoxy and some 
striation (in some periods and places at any rate) are abundantly 
common on crypton more than phaneron. That a similar statement 
would be true as to the variation of crypton in Brenthids (euphrosyne, 
etc.) (aberrant as to melanic and obsolete uppersides) being more 
common than of phaneron, one is not prepared to urge too strongly, 
but as to the less variability of undersides in Brenthids, one has a few 
definite details to offer. Indeed, it seems quite a notable point. 
In euphrosyne and selene aberration of the underside is sometimes 
limited to the crypton. But it may be quite as limited on other lines. 
Whereas with a fairly or even fully developed recurrent form of aber¬ 
ration one may easily obtain access in collections to, say, fifteen or 
twenty with fairly normal undersides for one example with any aber¬ 
ration of the underside at all comparable in extent with upperside—it 
is only in the most replete collections that the latter occur, except 
singly, viz., aberrations of uppersides with notably aberrant undersides, 
and some even of the most advanced upperside aberrations are accom¬ 
panied by normal undersides, just as though a marked aberration of 
an upperside was more readily produced than as marked an one on the 
underside. One specimen only has one seen or heard of, viz., euphrosyne, 
with marked underside aberration and normal upperside. And 
further, the marked aberrations of English Brenthids fall into four 
quite distinct categories, or rather five, inasmuch as two or more of the 
forms may be mixed in an aberration. 
The forms are (1) confluence of extended markings; or such 
transposition and alteration (2) as to form a new pattern of markings; 
and (3 and 4) totally opposed conditions, disappearance of many or all 
of markings, leaving ground colour, more or less, only on the one 
hand, and melanism or such extension of black markings as largely or 
wholly to efface the ground colour in parts or on the whole wing. 
With all these varied forms of upperside variation, with only one 
exception, has one ever seen more than one single form of underside 
variation, viz., more or less extension of the silvery markings over the 
interneural spaces, with the darker markings more and more obsolete 
to full degree of being represented only by dark and widened neutral 
lines. The one exception is a selene in the Webb collection, largely 
melanic on underside as v r ell as on upper.Moreover, with all the 
variations in aberrations of selene and euphrosyne, the underside aber¬ 
ration described above is common to both species. 
On the undersides of selene and euphrosyne, with the exception of 
sexual dimorphism, but little variation (and not commonly) exists ; in 
minor degree an amount of darker colouring, and of black outlining, 
* In Tutt’s butterflies is figured an ab. of selene showing on underside some 
extension and confluence with border of extra median row of dark spots on hind- 
wings, making two forms of underside variation, besides the general melanism. 
XIX. 
