ANALYSTS. 491 



devised. The instrumenta ciharia are indeed as useful in- 

 dices of a natural arrangement, as any other organs what- 

 ever ; but absolute rules of generic distinction, founded on 

 their minute differences of structure, are not only faulty in 

 themselves, but calculated to blind us altogether to those 

 beautiful groups which the Entomologist has so often oc- 

 casion to remark in nature. 



In a tribe of insects feeding on dry food, every species 

 shall perhaps present a slight variation in its organs of man- 

 ducation from the nearest to it in affinity ; and in a tribe 

 feeding on juices, and therefore provided with membra- 

 naceous mandibles, insects the most opposite in external 

 appearance, shall present scarcely any difference in the 

 structure of their mouth. So also with the antennse : the 

 " clava Jissilis" makes the Linncean genus Scarabtsus one 

 of the most natural in Entomology, while the " data per- 

 foliata" and "antenna moiiilifonnes" make the genera 

 Dermestes and Tenebrio of the Si/ sterna Naturcz groups 

 worthy only of Mouflfet. Nay, this very adoption of one 

 principle of division — this prescription of a rule to nature, 

 was a cause moreover of the Linn^an and Fabrician ge- 

 nera, even when natural groups, having an insulated cha- 

 racter about them, utterly inconsistent with the abstract 

 idea which Linnssus, from the above botanical aphorism, 

 appears to have had of a genus. There is no appearance, 

 indeed, in the works of Fabricius, that this naturalist ever 

 had any abstract notion of a genus, or indeed any belief, 

 but that every division he in his good pleasure thought 

 proper to propose was a law of nature. Linnaeus, on the 

 contrary, undoubtedly had both a theoretical and a prac- 

 tical genus, the latter of Avhich was the invariable result 

 of his attempts to carry his idea of the former into effect. 



