458 Mr. R. M‘Lachlan’s Observations on 
these supposed species should probably be referred to Sterrha 
sacraria, for most of them really approach more nearly to the 
typical form of that species than do most of the bred examples.* 
I deeply regret that Mr. Hellins was unable to obtain eggs 
from these examples, so as to prove if they would continue to 
vary in like manner, or would all or in part revert to the typical 
form, for I cannot but consider it a very extraordinary circum- ~ 
stance that not one of them should have in any degree approached 
to this form. ‘To what are we to attribute this variation? I 
ask the question, but confess that I see no satisfactory method 
of answering it. ‘‘ Unusual food-plant” will no doubt be sug- 
gested by some. I cannot admit this explanation, because I have 
no belief in the power of the food of the larva to produce any 
immediate and striking effect upon the imago; such an effect 
must be the work of ages, combined with previous isolation ; 
besides as S. sacraria is almost cosmopolitan, even the typical 
form, it is reasonable to suppose, is by no means confined to 
any one plant. I rather look to climate, but here again I do 
not understand the immediate effect. It may be worth remarking 
that these examples show precisely the peculiarities that one 
would expect in a delicate tropical or semi-tropical species 
adapting itself to a colder climate, for their texture is denser, 
and their general form more robust. 
I will now make a few general remarks on variation in Lepidop- 
tera, chiefly based upon observations of British species. Britain 
has been emphatically styled by Guenée “le pays des variétés,” 
and it is well known that British specimens are always desired by 
continental collectors. Indeed I could not help remarking, when 
looking over some of the Parisian collections, on the absence 
from or rarity in them of what we are wont to consider as 
the typical forms of many species. This great richness in 
varieties may be due, first, to our insular position; secondly, to 
our anomalous and variable climate; and thirdly, and perhaps 
chiefly, to the diversity in the geological structure of these islands. 
I, of course, place out of the question sexual variation, and also 
the so-called cases of “hermaphroditism” or “ gynandromorphism,” 
* This suggestion is of course based on incomplete evidence; for should 
the larve of these forms prove to be constantly distinct from each other and 
from that of S. sacraria, that would establish the right of all or any of them 
to be considered as species. I may add that, through the kindness of 
Mr. Doubleday, I have examined specimens of anthophilaria received from 
Dr. Staudinger ; these differ from any variety of sacraria that I have seen in 
the direction of the oblique fascia, which leaves the costa before the apex, 
whereas in sacraria it leaves the costa at its junction with the apical margin. 
