104 On the Land and Fresh Water MoUusca 



Pupa musconim means in any catalogue, it becomes necessary, in 

 the first place, to know what authority the writer follows. Some 

 species of Helix, Planorbis, and Limneus are in a similar predica- 

 ment. It is certainly better in such a case to drop the disputed 

 name altogether, and adopt another about which no doubt exists. 

 A great preponderance of authority may, however, sometimes in- 

 duce us to retain it. 



Important as uniformity of nomenclature is on all hands acknow- 

 ledged to be, it would be no easy matter to establish it. The days 

 are past when the authority of one great name was sufficient to carry 

 with it the acquiescence of admiring followers. Science is now a 

 republic, and were Linnaeus himself to rise from the dead, he 

 would fail to accomplish such an object. It is worth while consider- 

 ing, however, whether a congress of the leading naturalists in each 

 department might not, by mutual concessions, be brought to agree 

 upon adopting a uniform set of specific names. If this were done a 

 great deal would be accomplished towards inducing succeeding 

 writers to adopt the same convenient plan. I mention specific 

 names only, because it is clear that those of general and higher 

 groups, being founded upon our knowledge of nature, must be left 

 to be modified as that knowledge increases; but specific names are 

 mere conventional and arbitrary signs j more or less valuable, indeed, 

 according to their indication of character, yet such as when once 

 adopted it is not necessary afterwards to change. The subject is 

 well worthy the attention of the natural history section of the 

 British Association. I have been led further into the consideration 

 of this subject than is altogether necessary for my present purpose ; 

 but the evil complained of is a serious one. Were this obstruction 

 to our progress once removed, and a set of well digested rules agreed 

 upon, we have a guarantee in the increased and increasing facili- 

 ties of communication now established between naturalists of all 

 countries, and the greater accuracy of description now adopted, that 

 such a barrier would not again arise to obstruct our path, or deter 

 the youthful inquirer from entering upon the fair field of natural 

 history. 



It has been attempted, as far as practicable, in the following list, 

 to give, after the name of the genus, that of the author who first 

 instituted it ; but where it has been afterwards restricted, a second 

 name is given, indicating the author who used it in the restricted 

 sense in which it is at present taken. In like manner, after the spe- 

 cific name is placed that of the author who imposed it, without any 

 reference to the genus in which it is now used ; but where the ge- 

 neric appellation has been changed, the name of the author first 

 applying it in that genus is also added. 



