o 



8 The Field Naturalist's Quarterly Feb. 



lands afar, but are at the present so well established as to 

 have become naturalised : most of these, unlike a beetle 

 called Lcmostenus, suddenly found to be not uncommon 

 with us so late as last year, which, from its constant occur- 

 rence in the vicinity of seaports, I regard as appertaining to 

 this denomination, are by no means desirable acquisitions to 

 our fauna. All or nearly all our noxious kinds upon investi- 

 gation will be found to have been introduced : the cockroach, 

 though common in London cellars so long ago as 1634, 1 is 

 undoubtedly of Eastern origin. Lastly, there are all those 

 which we are led to believe have bred and evolved ex- 

 clusively in Britain ever since its severance from continental 

 Europe ; and in this respect it is curious to note how closely, 

 in many cases identically, our species have through the 

 length of the ages followed the lines of their trans-marine 

 relatives, and how few forms there are which do not also 

 exist somewhere abroad : thus among our four or five 

 hundred larger moths only five are known to be exclusively 

 British " species." 



In their study of distribution the collector and philosopher 

 meet, — the former to search in varying climates and upon 

 distinct formations for species only found under such con- 

 ditions, the latter to tell him why they should be there alone 

 discovered. In it the nomenclator has no place : his duty 

 it is to differentiate between the forms discovered, to note 

 what are and what are not constant characters in any given 

 group — for points which are invariable in one will sometimes 

 differ widely, not only in another group of species, but even 

 in a single kind. His task is none of the lightest, for he must 

 familiarise himself with all that has been written throughout 

 the world upon whatever group he is studying ; he must 



1 " When the first Asiatic cockroach set foot in Britain, it is impossible to say 

 with certainty, but it was probably not more than about four centuries ago. By 

 the end of the sixteenth century, they had been introduced into the two chief 

 maritime countries of Europe — England and Holland ; but we do not get any 

 specific notice of them in zoological literature till near the middle of the seven- 

 teenth century, when we read of them as found in flour-mills, wine-cellars, &c, 

 in England. At this early date, it was, of course, only the seaport towns, and 

 principally London, that were frequented by the insect, and it took a long time to 

 spread to inland and country districts — indeed, in all probability, the conquest 

 of England by the cockroach is hardly yet complete." — E. A. Butler, 'Our 

 Household Insects,' p. 117. 



