MASON : VARIATION IN THE SHELLS OF THE MOLLUSCA. 345 



Now, one word as to varietal names. Although 

 Names are good, for how, without their aid. 

 Is knowledge gained by man to man conveyed ? 



It is possible out of a large number of specimens of the same 

 species to pick out examples which contrast strongly with one 

 another, and to label them with distinctive names. 



In the arrangement of a large collection, however, these 

 names, which at first seem to be a means of accurate description, 

 become a source of confusion, as every gradation may be 

 observed to exist between the different forms. This, however, 

 is a mere matter of convenience, and every one must be a law 

 to himself. 



In these days, nearly all work except that done by the 

 microtome and microscope, is looked down upon as somewhat 

 unworthy of serious attention, although, with the present per- 

 fection of mechanical appliances, no work is much easier than 

 that of section-cutting. I believe that the work, humble though 

 it may be, of those who examine the alterations of external form 

 have a distinct and useful place in the study of nature, if only 

 to prevent the microtomist from treating dissimilar forms as 

 distinct species, while they are essentially the same. No one is 

 competent to undertake the discrimination of allied forms who 

 has not been exercised in what an American writer well called 

 ' the dead work of science,' that is, the examination and separa- 

 tion of large numbers of specimens. I recently read an offer, 

 by a gentleman, of a large amount of material dredged in the 

 Indian Ocean, to any one who would thoroughly work it, as he 

 was unable to do so himself. This offer was, however, accom- 

 panied by a notice that ' No species-maker need apply.' 



When the dust-heaps of science come to be riddled and the 

 dross separated from the ore, I have no fear that as large a 

 proportion of the work done by the species-maker and variety- 

 monger will prove to be as good metal as that brought forward 

 by the pedigree-maker and the so-called philosophical naturalist. 

 The epoch-making labours of Darwin depended on the observa- 

 tion of small differences ; and he who has first thoroughly 



