IG THE NATURAL HISTORY OF THE COMMON CRAYFISH. 



we put the Christian name, so to speak, after the sur- 

 name. 



There are a numher of kinds of Crayfish, so similar 

 to one another that they bear the common surname of 

 Astacus. One kind, by way of distinction, is called 

 fluviatlle, another slender-handed, another Daiiric, from 

 the region in which it lives ; and these double names are 

 rendered by — Astacus JiuviatiUs, Astacus leptodactylus, 

 and Astacus dauriciis ; and thus we have a nomenclature 

 which is exceedingly simple in principle, and free from 

 confusion in jiractice. And I may add that, the less 

 attention is paid to the original meaning of the sub- 

 stantive and adjective terms of this binomial nomen- 

 clature, and the sooner they are used as proper names, 

 the better. Ver}^ good reasons for using a term may 

 exist when it is first invented, which lose their validity 

 Avith the progress of knowledge. Thus Astacus Jluviatilis 

 was a significant name so long as we knew of onh' one 

 kind of crayfish ; but now that we are acquainted with a 

 number of kinds, all of which inhabit rivers, it is meaning- 

 less. Nevertheless, as changing it would involve endless 

 confusion, and the object of nomenclature is simph' to 

 have a definite name for a definite thing, nobody dreams 

 of proposing to alter it. 



Having learned this much about the origin of the 

 names of the crayfish, we ma}'^ next proceed to consider 

 those points which an observant Naturalist, who did not 



