PREFATORY NOTE TO YOLUME SECOND.
P R I N T E D B Y T A Y L O R A N D F R A N C I S ,
RED L ION COURT, F L E E T S T R E E T .
S i n c e the publication of the First 'Volume of this Work, tlie
researches of Naturalists and Microscopists have considerably
extended the number of British species belonging to the genera
therein described. I have appended a list of these to the present
volume ; but I feel satisfied that much yet remains to be
done before this field of inquiry can be regarded as sufficiently
explored.
Under these circumstances, I have thought it better not to
detain the publication of this volume for the engraving of the
additional forms already discovered in the British Isles, as this
delay would probably render nugatory the attempt to give the
work the character of a complete monograph ; but to look forward
to an opportunity of preparing a Supplement, bringing
down the subject to a more advanced stage of observation and
inquiry.
For the same reason I abstain from indicating the alterations
in the specific arrangements and synonymy of the First Volume,
that an acquaintance with new forms and continental specimens
would seem to justify or require, as each day supplies fresh
materials for a correct judgment, and enables me to modify or
confirm with greater certainty the opinions I have akeady
recorded.
The great interest taken in the subject of British Diatomaceæ,
a 2