INTRODUCTORY. 



15 



been pleased to term " nervures." It results 

 from a careful examination of the writings 

 of entomologists, that exactly one third have 

 described these supports as "veins," exactly 

 one third as " nerves," and exactly one third as 

 " nervures," or " nervules "; the advocates for 

 each term having shown to their own entire 

 satisfaction its peculiar and exclusive propriety. 

 The argument always runs thus : " We know 

 very well that these organs are not veins (or 

 ' nerves', or ' nervures,' as the case may be), 

 but it is a matter of convenience so to deno- 

 minate them ; and no sensible man will deny 

 the advantages of a uniformity in anatomical 

 nomenclature." This reasoning appears to 

 me somewhat illogical: if we "know very 

 well " that the wing of a bird is not a leg, it. 

 can be no convenience to any one to call it a 

 leg ; if we " know very well " that the head 

 of a horse is not its tail, it really can be no 

 convenience to call it a tail. We know 

 exactly the use and object of these supports : 

 it is precisely the same as that of the fin-rays 

 of a fish, which are invariably called " rays," 

 and therefore, wherever I have had occasion 

 to mention these rays, either in the present 

 " history," or in that previously published of 



the " British Moths," I have invariably called 

 them " rays " a term which I venture to 

 hope all my readers will accept, since they 

 cannot fail to understand. 



EXPLANATION OF TERMS. 



With the single exception of wing- rays, 

 which my readers will please to understand 

 as precisely equivalent to the fin-rays of 

 fishes, I shall use no terms except those of 

 universal acceptation when speaking or writing 

 of insects ; and I could wish that I had no 

 occasion to use a single word that could not 

 be found in Johnson's Dictionary ; but this is 

 very difficult, and I find, after every endeavour 

 to avoid the use of new words, or of applying 

 new meanings to old words, I am absolutely 

 compelled to do that which I have the most 

 anxious desire to avoid. It is no common 

 achievement to have removed so many of those 

 stumbling-blocks to the acquisition of scientific 

 knowledge italics, abbreviations, and signs ; 

 this is happily accomplished, and we must 

 content ourselvas therewith, and not quarrel 

 over a few unusual words, but endeavour to 

 make them both familiar and intelligible. 



Explanatory Figure of a Butterfly. 



In order that the terms used in describing 

 may be rendered as intelligible as possible, I 



have drawn the outline figure of a butterfly, 

 and indicated by letters the different parts J 



