VI. PREFACE. 



priority, called Celerio gallii, populi — Amorpha populi, tiliae — Mimas 

 tiliae, and so on, yet Messrs. Rothschild and Jordan term the 

 species we call Hemaris fuciformis, Haemorrhagia fuciformis, the 

 species that we call Sesia stellatarum, they know as Macroglossum 

 stellatarum, and these differences are only typical of many others. 

 These divergences arise from three causes : (i) The entirely different 

 way in which we select the types of the various genera. (2) The 

 subdivision of certain genera by one held to be inseparable by 

 the others. (3) The rejection by these authors of Hiibner's Tentamen, 

 which they urge contains only " nomina nuda." Their mode of 

 selection of the type of a genus is easy if not scientific, for they 

 consider the species placed in the first position in the genus by 

 the author, the type, whether or not such species agrees with the 

 diagnosis of the genus, or whether the species was or was not known 

 to the author. There is much to be said for this mode of selection 

 of a type, for the most ignorant lepidopterist can do it as satis- 

 factorily as the most learned, it does away with the need of either 

 knowledge or brains, and the type-fixer need not determine which 

 species of the genus were really before the author when naming the 

 genus, nor which species were afterwards added by him as possible 

 members of his genus from descriptions or the examination of the 

 figures of other authors, the species being unknown to him in 

 nature. Neither does he need to trouble himself about the 

 action of the original author's successors, nor consider their work. 

 By this amazing method ocellata becomes the type of Linne's genus 

 Sphinx, although Linne himself shows us that he obtained the name from 

 Reaumur and intended it specially to apply to ligustri. The " Merton 

 Rules" insist that the " type" of a genus must not disagree with the 

 description of the genus, and shall be considered as that species 

 on which the generic diagnosis was essentially or mainly based, 

 so far as is compatible with an acceptance of subsequent revisions, 

 in their chronological order — which is the only true " law of priority." 

 This appears to us both sound logic and commonsense. It 

 requires, of course, in most cases, knowledge and intelligence to 

 settle these points, and it follows that the type can only be 

 determined by those who know. It is true that the fixing of 

 the type by this means is not automatic, it may lead to difference 

 of opinion and, therefore, has drawbacks. Without wishing to 

 defend the method adopted further, we will only add that, with 

 the publication of the " Merton rules " we had hoped that the 

 workers at the British Museum and our leading lepidopterists 

 would have been guided by their principles and a large measure 

 of uniformity attained. Vain hope ! Every lepidopterist who has 

 reached a certain standard of work, knows how to construct rules 

 that shall lead to uniformity better than every other lepidopterist, 

 and the result is that almost everyone has his own independent 

 method. To us the whole matter appears egotistical ; at least the 

 leading British workers could readily agree to an uniform code, 

 but, evidently, whilst everyone cries aloud for an uniform nomen- 

 clature, the criers take every possible precaution not to get it. 

 Those differences that arise from a subdivision ol genera, the 

 natural outcome of a close study of the species involved, are 

 of much less importance, for they are largely the result of the 



