W/-V I August, 
Additions to Mr. Bi/rchalVs list of the Lepidoptera of Ireland.— Sesia pUlanthi- 
formis freely on the coast at Howth, from the Baths to the Round Tower in Dublin 
Bay, where the sea-pink {Statice armeria) grows upon the rocks. June and July. 
Pempelia subornatella, Zeller, plentifully on the rocky places on the slopes 
where Sedum grows in the above-named locality. I fancy that this insect has 
been mistaken for P. dilutella in the above-named list, and also for ornatella, neither 
of wliich have been met with by me at the Hill of Howth. June and July. 
It would be very interesting if both dilutella and ornatella were proved to be 
entitled to be retained in the Irish list ; the former is said to be a Southern species, 
the latter a Scotch one, from Arthur's Seat, Edinburgh, or Duddington, and was 
discovered some years ago by my old friend Mr. Logan : both of them are very 
distinct from subornatella. — C. S. Gregson, Stanley, Liverpool. 
*^* P. ornatella occurs pretty commonly at Sandgate, on the south coast. — H. G. K. 
Notes on variations. — The question of varieties and their causation is just 
now attracting great attention, and is undoubtedly well worthy of it. The term 
variety is, however, a very wide one ; and it is very evident that a cause pro- 
ducing one sort of variety may be totally inoperative as regards another sort : for 
this reason it is, I think, desirable to obtain some more limited and definite use of 
the word ; and, in order to do this, I would call attention to the fact, that there 
appear to be three tolerably distinct and definite kinds of variation, viz., race, 
variety, and aberration. 
A race is generally found under evidently somewhat different circumstances to 
the type form of the species to which it belongs, and is distinguished by constant 
though slightcharacters ; butspecimens forming thepassage from the race to the type 
occur, though in many cases very rarely. As instances of race, Bomhyx callim(B 
and Bembidimn riparium may be mentioned. The second kind of variation, and to 
which the appellation variety should be limited (though it would be better to find 
a fresh term for this form, and use the word variety in a generic sense, as including 
all the three forms of variation), is a form which a species has a tendency constantly 
to assume, independently of locality and of its immediate ancestry. As a good 
instance of it may be mentioned the var. spurcaticornis of Anisodactylws hinotat^ws ; 
this variety appears to occur wherever the type occurs, but never away from it. 
The third kind of variation or aberration is a slighter and less constant form 
than the preceding ; variations of colour, and such like circumstances, in individual 
specimens, are instances of what I mean by aberration. 
A moment's consideration will be sufiicient to convince us that it will take 
very different causes to produce an aberration and a race. 
An aberration is the only form of variation that can be produced readily by 
experiment or by accident (i. e., a slight change of conditions of Life) ; and it is a 
very interesting fact that, while some species are very subject to aberration, in 
other species it does not occur : there is, I believe, a reason which could be assigned 
for this ; I will not consider it now ; but I think a list of the species of British 
Lepidoptera most subject to aberration, and another of those least subject to it, 
would be very interesting and instructive. 
A race, it will be seen from the definition I have given of it, approaches very 
nearly in validity to a species ; indeed the connecting forms ai*e the only 
reason that can satisfactorily be assigned for its non-distinctness. It is, in fact, a 
species nearly formed ; and it is probable that, under a somewhat greater differentia- 
tion of the circumstances in which the type and race live, intermediate examples 
would cease to occur, and the race would become a distinct species. 
The second form of variation or variety is apparently the most inexplicable one 
