■V PR E FA T O R Y N O T E TO V O L . I I .
by observers so competent and laborious as Drs. Greville, Arnott,
Gregory and others, and the liberality with wliich their discoveries
and opinions are conimmiioated to tlie public and myself,
justify tlie expectation wliicli I entertain of being able shortly
to increase the utility of my work by a valuable accession of
new facts and new forms.
I think it right in this connexion to state, that I have no
additional evidence enabling me to receive the genus Dictyocha
as belonging to the Diatomaceæ, and that various features in
the structure of the species arranged under the genera Climto-
ceros, Goniothedum, and their allies, constrain me for the present
to refuse such forms admission into the present work. An admirable
paper by Mr. Brightwell on the British and Foreign
Species of some of these genera may be found in the ‘ Microscopical
Journal’ for January 1856, and will, it is to be hoped,
direct the attention of Naturalists to the determination of the
true character and position of these singular organisms.
Queen’s College, Cork, March 1856.
CONTENTS OF TH E INTRODUCTION.
Page
S e c t io n VIII. On Reproduction in the Diatomaceæ . . . . vii
IX. On the Nature of the D ia tom a c eæ .................. xvii
X. On the Determination of Species in the Diatomaceæ
........................................................................... xxi
XL The Distribution and Uses of the Diatomaceæ . xxvi