248 ESSAY ON CLASSIFICATION. 



genus, whenever its characters do not agree with the 

 characters of other species, and many species may con- 

 stitute a genus, because their specific characters agree to 

 a certain extent among themselves. 1 Far from admitting 

 such doctrines, I hope to be able to show, that, however 

 much or however little species may differ among them- 

 selves as species, yet they may constitute a natural genus, 

 provided their respective generic characters are identical. 

 I have stated before, that, in order to ascertain upon 

 what the different groups adopted in our systems arc 

 founded, I have consulted the works of such writers as are 

 celebrated in the annals of science for having characterized 

 with particular felicity any one kind of these groups ; and 

 I have mentioned Latreille as prominent among zoologists 

 for the precision with which he has defined the genera of 

 Crustacea and Insects, upon which he has written the 

 most extensive work extant. 2 An anecdote, which I have 

 often heard repeated by entomologists who knew Latreille 

 well, is very characteristic as to the meaning he connected 

 with the idea of genera. At the time he was preparing 

 the work just mentioned, he lost no opportunity of ob- 

 taining specimens, the better to ascertain from nature the 

 generic peculiarities of these animals; and he used to 

 apply to the entomologists for contributions to his collec- 

 tion. It was not show specimens he cared to obtain ; any 

 would do, for he used to say lie wanted them only " to 

 examine their parts." Have we not here a hint, from a 

 master, to teach us what genera are, and how they should 



1 SPRING, Ueber die naturhistoris- DANA (J. D.), Thoughts on Species, 



chen Begrifte von Gattung, Art und Amer. Journ. Sc. and Arts, 1857, vol. 



Abart; Leipzig,1838 3 lvol.8vo. BUR- 24, p. 305. 



MEISTER (H.), Zoonomische Briefe ; 2 LATREILLE, Genera Crustaceo- 



Leipzig, 1856, 2 vols. 8vo, WOLLAS- rum et Insectorum; Paris, et Ar- 



TON (T. V.), On the Variation of gent., 1806-1809, 4 vols. 8vo. 

 Species; London, 1856, 1 vol. 8vo. 



