39 



The color of a shell may, to a very great extent, depend 

 upon that function of the mantle involved in the produc- 

 tion of the epidermis. It may also be to some extent in- 

 fluenced by the properties of the water in which the mol- 

 lusc lives. 



It will be seen that there are numerous conditions which 

 may affect a single species and cause it to be presented 

 under such aspects as to create the impression that differ- 

 ent local forms are different species. Much has been done 

 in the direction of synonymy, but without doubt, equally 

 as much more remains to be done. It may also be sug- 

 gested that a few errors have crept into synonymy, as it is 

 now received, and the work needs revision. In a class of 

 shells embracing so many species, presented under the dif- 

 ficulties that beset the Strepomatidse, it will be impossible 

 to do more at present than suggest inquiries. The brief 

 hints that occasionally appear in the list of species are all 

 that it seems expedient to suggest at this time. 



