;2 :'J /'/';' ; /, INTRODUCTION. 



have been drawn by' my brother Gerald "W. Adams, a 

 collector like myself. Most of the drawings have been 

 taken from shells in my own cabinet; here and there, 

 however, a friend has been generous enough to lend me 

 some fine or rare specimen to copy. 



Where there is no " size-line " the figures may be taken 

 as life size, except in the case of the three largest bivalves, 

 which for convenience sake I have figured smaller than 

 the average size of adult specimens. In these cases I have 

 stated their dimensions beside the figures, and also in the 

 descriptions. 



I have translated and accentuated the specific names of 

 all the species, and have appended a glossary of all the 

 technical terms which I have been compelled to make 

 use of. 



It should be borne in mind that plates and descriptions 

 are at best but a second-rate substitute for a direct exami- 

 nation of the objects themselves, and that far more may be 

 done towards the identification of difficult species by careful 

 comparison with a good collection of well-authenticated 

 specimens, than by working at plates and descriptions 

 alone ; just in the same way that more correct and useful 

 knowledge of anatomy may be gained and fixed in the 

 memory by a couple of hours' dissecting than in a week of 

 poring over the best diagrams. 



Most of our large towns, and many of the smaller ones, 

 boast of some sort of museum where British shells have a 



