In a book of this character it is almost impossible to avoid some errors, but it is hoped that these will be comparatively few. In correcting the proof-sheets I have received invaluable assistance from Dr. Warming and Dr. Knoblauch, who have kindly read through every sheet, and to whom I am greatly indebted for many criticisms and suggestions. I have also to thank Mr. I. H. Burkill for his kind assistance in looking over the proofs of the Monocotyledons and Dicotyledons, and Mr. Harold Wager for kindly reading through the proofs of the Algæ and Fungi. My thanks are also especially due to Mr. E. L. Danielsen, and I wish to take this opportunity of acknowledging the very considerable help which I have received from him in translating from the Original Danish. M. C. POTTER. _January, 1895._ TABLE OF CONTENTS. BEING THE SYSTEM OF CLASSIFICATION ADOPTED IN THE PRESENT VOLUME. (_The Algæ and Fungi rearranged in co-operation with Dr. E. Knoblauch, the other Divisions as in the 3rd Danish Edition._) PAGE DIVISION I. THALLOPHYTA 4 A. Sub-Division. Myxomycetes, Slime-Fungi 5 B. Sub-Division. Algæ 8 Class 1. SYNGENETICÆ 14 „ 2. DINOFLAGELLATA 16 „ 3. DIATOMEÆ 18 „ 4. SCHIZOPHYTA 22 Family 1. Schizophyceæ 22 „ 2. Bacteria 26 Class 5. CONJUGATÆ 41 „ 6. CHLOROPHYCEÆ 46 Family 1. Protococcoideæ 47 „ 2. Confervoideæ 53 „ 3. Siphoneæ 59 Class 7. CHARACEÆ 64 „ 8. PHÆOPHYCEÆ (OLIVE-BROWN SEAWEEDS) 68 Family 1. Phæosporeæ 68 „ 2. Cyclosporeæ 73 Class 9. DICTYOTALES 76 „ 10. RHODOPHYCEÆ (RED SEAWEEDS) 77 Family 1. Bangioideæ 77 „ 2. Florideæ 78 C. Sub-Division. Fungi 84 Class 1. PHYCOMYCETES 96 Sub-Class 1. _Zygomycetes_ 96