Vlll PREFACE. 



admeasurement I have considered preferable to statinj 

 the largest dimensions to which each species attains 

 which would not give a fair idea of the usual size, or t< 

 adopting the method used by some Continental author 

 of giving the range or extreme limits of such dimensions 

 Any extraordinary difference of size presented by speci 

 mens or varieties will be noticed. In giving the ad 

 measurement of bivalve shells, I have considered th 

 length to correspond with the line of growth (viz. fror 

 the apex or beak to the front margin), and the breadt 

 from one side of each valve to the other. In the case c 

 univalve shells I have adopted the same rule, viz. takin 

 the line of growth for the length (the apex or point c 

 the spire representing each beak of the bivalve), and th 

 widest part of the shell, or its greatest diameter, for th 

 breadth. 



At the end of the work I propose to give some prac 

 tical hints to collectors. 



For the benefit of such of my lady readers as have nc 

 added a knowledge of the classics to their other accom 

 plishments, I have marked the accentuation of all th 

 names of genera and species described in this work. On 

 word of frequent occurrence I have noticed to be to 

 often mispronounced by many who ought to know bettei 

 and that is the specific name of our common eatabl 

 oyster, mussel, and cockle. This word (edtilis) has th 

 middle syllable long, as is evident by remembering on 

 of the various gastronomic maxims of Catius, "Vine 



