36 



INTRODUCTION. 



any other assistance than that derived from long experience, 

 because the most nearly allied species possess such a gene- 

 ral resemblance to each other, that it is almost impossible to 

 overlook their relationship : for instance, the restricted genus 

 Carahus comprises a very extensive series of ground-beetles, 

 varying but little in size (com- 

 pared with the variations in size 

 which occur in the family), being 

 moderately large, and orna- 

 mented more or less with me- 

 tallic tints ; so also among but- 

 terflies, the genus Colias com- 

 prises species being generally of 

 a brimstone colour. We now 

 arrive at the investigation of the 

 specific name of the insect un- 

 der examination ; and here lies 

 a great difficulty, owing in gene- 

 ral to the number of species ; 

 great relief, however, is afforded 

 by the introduction of subdivisions in the longer genera, by 

 which we arrive almost immediately at the name of the spe- 

 cies itself. In general the descriptions of insects are written 

 in Latin, or at least, if an author chooses to give a specific 

 description in his native tongue, it seems by common consent 

 and usage to be required that he should commence his de- 

 scriptions by a short Latin character, which, from the almost 

 universal employment of that language in works of natural his- 

 tory, is intelhgible to naturalists throughout the world. More- 

 over, the indication of the natural length and expansiou of 

 an insect, the addition of the country which it inhabits, and 

 the references to the works of other authors by whom the 

 species may have been described, and especially where it lias 

 been figured, all tend to render this branch of the scic ice 



Cnrabus clathratus. 



