qq introductory remarks. 



ticular, for this genus appears to me capable of 

 furnishing the best of all possible criterions for the 

 trial of his system. The instrument a ciharia are so 

 conspicuous in most of the species that compose it, 

 and so easy to be examined, that if he has made 

 any mistake of consequence in the characters of 

 this genus, it is evident that dependance cannot be 

 placed upon those which he has assigned to others, 

 where the organs, upon which he builds his system, 

 are less obvious. It is not allowable to adopt, as 

 a gratuitous assumption, that these organs are not 

 subject to variation ; and so to construct charac- 

 ters from them, as they appear in one or two spe- 

 cies only, trusting solely to habit for the arrange- 

 ment of the rest : but the several results of a care- 

 ful inspection of them, in as many different indi- 

 viduals as possible, taken from all the subdivisions 

 of a genus, should be attentively considered and 

 compared, and the agreement and disagreement of 

 them accurately noted. This is the only sure 

 ground to go upon, and thus alone can it be 

 ascertained whether any, and which, of these 

 organs supply characters that are certain and con- 

 stant. It will soon appear that Fabricius Jbas not 

 taken these pains with respect to those genera into 

 which he has divided jipis. These are Bemhex, 

 Hylceus, Andrena, Apis, Eucera, and Nomada. 



The first of these, Bembex, I shall pass by, as it 

 consists chiefly of insects taken from Vespa, and 

 includes only one Linnean Apis, which_, as far as 



I can 



