— 422 — 



preserving for future study such material as sliall truly 

 represent the variation of the (» species ». A « shell beach » 

 of course afïords fairly satisfactory and easily obtainable 

 évidence as to whatforms inhabit the district; but, the spéci- 

 mens contained therein are of very little use forresearch, 

 since they hâve mostly lost certain of Iheir characters, and 

 since examples from différent stations hâve ail become 

 so thoroughly intermingled that it is impossible to form 

 any correct idea of the variation of a species. As the resuit 

 of imperfect collecting it is not generally realised how 

 greatly the Mollusca vary in relation to their environment 

 even at stations which are quite close to each other. Thus 

 individuals living on the sandy portions of a sea-beach will 

 often difïer very perceptibly from other examples of the 

 same species occurring among adjacent rocks or mnd. 



The student of taxonomy requires to examine large 

 séries of spécimens ; and, thèse spécimens should hâve 

 been carefully collected so as to represent faithfully the 

 variation of the species at the particular station where 

 they were collected. The best way, in my opinion, by which 

 it can be assured that a séries shall be a true représentation 

 of the local form of a species is to gather rrerij spécimen 

 met with at the station in question until a sutTiciently 

 large number bas been obtained. This séries should then 

 be preserved intact and not mixed with other spécimens 

 obtained subsequently or at diiïerent stations, olherwise 

 its représentative character will be lost. For the reason 

 given above, the collecting nrea should be made as small 

 as possible and should not include any considérable diver- 

 sity of ground. S. P. 



