SPECIES. 63 



more important organs, but in the various arms with which 

 they are furnished. This is especially the case with the 

 cornuted species, and those which have the mandibles very 

 greatly developed. Here in many instances there appear to 

 be a series of individuals intermediate between the fully 

 developed species and the females, which are generally desti- 

 tute of these appendages. This is to be noticed in many 

 species of lamellicorn beetles, and in some of the Stapliy- 

 Imidse {Siagonium quadricorne). The Rev. Mr. Biu'rell also 

 observed it in another species of the same group [Bledius 

 armatus), of which he describes a variety with horns shorter 

 than the head, although usually longer, and which he was 

 even disposed to regai'd as a neuter, an opinion also en- 

 tertained by Mr. Haworth, who considered that such neu- 

 ters are far more frequent, even in the Ilymenoptera, 

 than hitherto imagined. Besides these, which appear to 

 be casual occurrences, there likewise exist what have been 

 termed permanent varieties in many species, the individuals 

 of which are found in situations different from the ordinary 

 type of the species, and it has been considered that these 

 variations have originated somewhat in a similar manner to 

 the varieties of domestic animals : but this may certainly be 

 doubted, because, in most domesticated insects, the common 

 house-fly for example, disseminated as it is over the whole 

 surface of the globe, and the hive bee, we find not the 

 least liability to vary ; and if this be not the case mth these 

 species, we can hardly attribute the production of varieties 

 in species, which are in nowise subject to the agency of man, 

 to a similar cause. 



The characters by which species are distinguished are very 

 variable, partaking indeed, in this respect, of the peculiari- 

 ties which we have noticed in oiu: obsen^ations upon generic 

 and sub-generic groups. In very extensive genera the dis- 

 tinctions of species are so minute, that it requires the most 



