Excerpt from The British Noctu?, Vol. 4: And Their Varieties, December, 1892
In presenting the last volume of this work to my subscribers, it may be well to draw attention to a few further incidental facts to which the writing of the book has directed my attention.
In the Introduction to Vol. I. I dealt with some of the "Probable causes of variation," in that to Vol. II. with some thoughts on the "Genetic Sequence in the Colours of Lepidoptera," and in Vol. III. with those phases of variation connected with the sexes of Lepidoptera, generally known as "Secondary Sexual Characters." In the present volume I propose dealing with matters which need explanation, or have already had attention drawn to them, as well as a general idea of the classification of our Noctu? and their relation to those of other countries.
Varieties and Aberrations. - Some entomologists lay great stress on the distinction between "aberrations" and "varieties" and I think very properly, although I have been unable to keep up so artificial a distinction in this work. According to the distinction as set up by Dr. Staudinger, "aberrations" are accidental forms, occurring occasionally with the typical form, whilst "varieties" are local races or modifications of the type, which they have supplanted in various localities. It is very evident, that in a work based on exact study rather than generalisations, the distinction to a great extent falls through, and almost all the "varieties" so-called, would be in reality "aberrations." But there is no real distinction in this direction. Even in our own country the "varieties" or local races of one district are "aberrations" in another and vice versa. Take for example Cuspidia psi. In London, the pale type of this species is very rare, and has been supplanted by a true variety or local race known as var. suffusa. A few miles from London, the pale type generally occurs, whilst a dark specimen of the variety suffusa is very rare. In such a locality, suffusa becomes purely an aberration in the Staudingerian sense, and therefore within a few miles area, this form may be a variety (local race) or an aberration (occasional form). Every entomologist could give other examples - Cuspidia leporina and its var. bradyporina, Cymatophora or and its var. scotica, Thera juniperata and its var. scotica, Asphalia flavicornis and its vars. scotica and galbanus and endless other species give parallel instances. It becomes clear, therefore, that such an arrangement is exceedingly artificial and indefinite, and altogether unworkable, when the variation of most of our species is closely and systematically worked out.
Perhaps in another sense, almost all our British specimens of a very large proportion of species are "varieties" in the Staudingerian sense, i.e., if we compare them with the generally brighter and better marked typical forms obtained in Central and Southern Europe, for there are very few of our British species that do not differ from the usual Continental forms of the same species, and that do not bear a strong impress of the insular character of our fauna.
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