2 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 
