126 THE ATRACHELIA. 



as the Blister Beetle or Spanish Fly ; it is a native of 

 the southern parts of this country, where it frequents 

 ash-trees ; but as the vesicating power of these beetles 

 appears always to increase in proportion to the heat 

 of the country inhabited by them, the Cantharides 

 used here are all imported from the south of Europe. 

 Several species nearly allied to the common Blister 

 Beetle are employed in the same way in different 

 parts of the world, and some of these appear even to 

 have advantages over it, as their external application 

 does not produce certain unpleasant internal sym- 

 ptoms, which usually accompany the use of the C. 

 vesicatoria. The species of the genus Meloe are also 

 employed as vesicants in some places, and in Spain 

 they are said to be often mixed with the true Blister 

 Beetle. When touched or alarmed they counterfeit 

 death, and at the same time emit a yellowish oily 

 matter from the joints of their legs. This possesses 

 a certain amount of vesicating power, and the oily 

 liquid which may be pressed from their bodies has 

 been recommended as a remedy for rheumatism. 



Whether it be that Nature delights in contrasts, or 

 that our principles of classification are faulty, certain 

 it is that the members of the second tribe of Hetero- 

 merous Beetles (or those in which the posterior tarsi 

 are composed of four, and the remainder of five joints) 

 differ, as a general rule, most remarkably both in form 

 and habits from the active, gaily-coloured, and sun- 

 loving insects, which constitute the majority of the 

 preceding tribe, from which they are readily distin- 

 guished by having their heads immersed in the 

 cavity of the prothorax nearly as far as the eyes. 



