tvith particular regard to the Danish Fauna, 187 



the present vacillating characters of habitus; nor do these cha- 

 racters range together all those genera which, by the structure 

 of their essential parts, belong together. 



In this respect I have found it necessary to return to that 

 point to which Fabricius carried our systematic knowledge, and 

 to continue where he left off; for it seems to me that his pene- 

 trating eye in this matter fixed upon the only true starting- 

 point. Nor did this at first escape Latreille, as indeed might be 

 expected from this excellent systematic author, wbose genius, 

 no doubt, was of the highest order, only wanting greater self- 

 reliance. But we cannot wonder that when Latreille, in his 

 forty-ninth year, had finished the stupendous studies of which 

 he has succeeded in condensing the results into the four 

 small octavo volumes of his master-work, ' Genera Insectorum 

 et Crustaceorum,' he did not, in the following years of his life, 

 with equal energy continue these researches, but was content, 

 in his numerous later works, to master the new material as well 

 as it could be done by means of his old treasure of knowledge 

 and experience. This treasure was rich enough to enable him 

 to the last to tower far over the heads of all his contemporaries. 

 But an attentive examination nevertheless shows that the im- 

 mense accumulation of material which took place in the first 

 decenniums of this century (particularly after South America 

 became more accessible to Europeans) by degrees more and 

 more distended, undermined, and at last entirely destroyed the 

 classification of Latreille^s younger days. In the * Regne Ani- 

 mal ' the old structure is hardly to be recognized, half destroyed 

 as it stands there, patched up and extended by numerous 

 slight additions, only incompletely answering their purpose, 

 badly harmonizing with the original simplicity of the structure, 

 obscuring and disfiguring its former noble features. Where 

 much time and labour would have been required in order to 

 treat the new material according to the old method, the more 

 difficult part of the work has been left undone, and new syste- 

 matic rubrics have been inserted, with far less care than formerly. 



It is true that the same may, generally speaking, be said of 

 Fabricius, on comparing those of his works which date from his 

 earlier days with his later publications ; but the case is different, 

 because his method, great as the progress was which it involved, 

 nevertheless by its very nature did not allow of extension beyond 

 a certain point without breaking down. The basis and purpose 

 of the Fabrician method was the genus as defined by the organs 

 of the mouth : " Genera tot sunt, quot similiter constructa in- 

 strumenta cibaria proferunt diversse species naturales '^ (Philos. 

 Ent. Dispos. § 6. 1). He did not doubt the existence of natural 

 groups of genera ("classes"); but maintained, "at nondum 



