64 INTRODUCTION. 



practised eye to separate them ; and indeed there arc some 

 groups, the species of which are so intricately blended to- 

 gether, that no two entomologists are agreed as to tlu-ir dis- 

 tinctness. The genus Nothiophilus (a genus of small Cara- 

 bidce) affords an instance of this. Until very lately it was 

 supposed to consist of only two British species. Mr. Curtis, 

 however, added another; Mr. Waterhouse increased the 

 number to eighteen, in a monograph published in the Ento- 

 mological Magazine ; whilst Mr. Stephens has subsequently 

 reduced this number to six. The characters which supply 

 specific distinctions are also very variable ; size, sculpture, 

 colour, markings, locality, general forms, are all employed, 

 and it often happens that a character, which in one group of 

 insects would be deemed of sufficient value to characterize a 

 genus, is in others only serviceable as a specific mark of dis- 

 tinction : thus in the genus Rhipicera (a group of exotic 

 beetles, with beautiful pectinated antennae), these organs 

 vary in the number of their joints ; whereas in the entire 

 section of the aculeated Hymenoptera the same number of 

 joints runs throughout the whole. 



In describing species of insects it is usual to give a short 

 character, embracing the most striking characteristics of the 

 species. This is ordinarily in Latin, that language hcin<r 

 generally regarded as peculiarly adapted to science, being 

 universally understood wherever science exists ; indeed the 

 neglect of this plan, which we often notice in French and 

 German, and sometimes in English authors, shows a disre- 

 gard to a settled and most convenient custom, enabling per- 

 sons unacquainted with those particular language* to identity. 

 in some degree, a species, although the more extended de- 

 scription may he \\ritten in either of these or any other 

 tongue. It is usual also to add the length of the body and 

 expansion of the wings, these admeasurements being taken 



