24 NOMENCLATURE. 



ent condition, with an infinite number of genera, a difference, no matter 

 how slight, should be sufficient reason for retaining the name instead of 

 coining a new one, which is just as likely to fall into the same category, 

 and resemble another name in a different department to as great an extent. 

 It will compel a little more accuracy in the very class of writers who are so 

 punctilious and so anxious that nothing should be named twice, but who are 

 constantly, in spite of this, making two equal three. 



The completeness or insufficiency of the diagnosis of a genus is a worth- 

 less reason for rejecting a generic name; we find all possible gradations 

 between a mere catalogue generic name and an admirably defined* sec- 

 tion. The impracticability of defining what a genus is, — for what two 

 naturalists, working in the same department, admit the same limits '.' — shows 

 the impossibility of applying to genera, as strictly as to species, the rules 

 of priority. In old generic divisions which the advance of science lias 

 subdivided, it is of course advisable to retain the old names for some one 

 section; but for which section? Here the most opposite views are cur- 

 rent, one party claiming that you can limit the old name to any group 

 of species of the original genus, the other that you must apply to these 

 old generic names the same rules which have been proposed by the British 

 Association, very likely long after the genus was established. The first 

 have, at any rate, in their favor, tin' practice of the authors themselves, 

 whom we find afterwards in their later works limiting their genera to any 

 group of species originally contained in it. Old names are frequently 

 thrown out on the occasion of such subdivisions, for not being grammatical, 

 or for not being spelled correctly. Should we throw out Brissus, as univer- 

 sally spelled by Latin authors, because they should have spelled it Bryssus, 

 then we must throw out a more modern genus Leiocidaris because it should 

 be written Liocidaris, or Echinopatagus because we should say Echino- 

 spatangus, or Nina and Metalia for which our lexicons furnish us no clew. 

 Let us remember that probably the greater part of our Zoological genera 

 is made up with the assistance of a Greek Dictionary, and its correspondent 

 parts joined to the best of our knowledge and belief; we can scarcely 

 expect to obtain in this way classical names which the old Greeks would 

 be willing to father. When, therefore, we take so much pains in presenting 

 to our readers the derivation of the generic names, we should rather call it 

 the composition. The meaning of words with the ancients has changed 

 with the course of time, exactly as we find it in our own language ; 



