CONTENTS OP THE INTRODUCTION. 



Section I. The Habitats and general Appearance of the Dia- 



tomacese xi 



II. Structure of the Siliceous Epiderm of the Diatoma- 



ceous Frustule xiv 



III. Internal Structure and Cell-contents of the Diato- 



maceous Frustule xix 



IV. Movements of the Diatomacese xxii 



V. Self-division in the Diatomacese xxiv 



VI. Terminology and Classification xxvii 



VII. On Collecting and Preserving Specimens of the Dia- 

 tomacese xxix 



3 9 3 5 9 



