Thanks, also, are due to Messrs. Macmillan & Co. for permission to use cuts from the "Cambridge Natural History," Parker and Haswell's "Zoölogy", and Murray's "Introduction to the Study of Seaweeds"; to Swan Sonnenschein & Co. for the use of cuts from Sedgwick's "Student's Text-book of Zoölogy"; to Wilhelm Engelmann for a cut from "Die natürlichen Pflanzenfamilien" of Engler and Prantl; to Little, Brown & Co. for permission to reproduce illustrations from Agassiz's "Contributions to the Natural History of the United States"; to Henry Holt & Co. for a cut from McMurrich's "Invertebrate Morphology"; to Houghton, Mifflin & Co. for cuts from the "Riverside Natural History" and Agassiz's "Seaside Studies in Natural History"; to the Commonwealth of Massachusetts for the use of illustrations from Verrill's "Report upon the Invertebrate Animals of Vineyard Sound and the Adjacent Waters," Gould's "Invertebrata of Massachusetts" (ed. Binney), and certain fisheries reports; and to the United States government for illustrations taken from Bulletin 37 of the Smithsonian Institution and from reports of the United States Fish Commission. CONTENTS INTRODUCTION PAGE I Signs on the Beach 1 II Collecting 6 III Classification 19 IV Animal Life in its Lowest Forms 21 V Distribution of Animal Life in the Sea 23 VI Some Botanical Facts about Algæ 25 VII Naming of Plants 28 VIII Distribution of Algæ 30 IX Some Peculiar and Interesting Varieties of Algæ 32 X Uses of Algæ 37 XI Collecting at Bar Harbor 40 PART I MARINE ALGÆ I BLUE-GREEN SEAWEEDS 47 (CYANOPHYCEÆ) GRASS-GREEN SEAWEEDS 47 (CHLOROPHYCEÆ) II OLIVE-GREEN AND BROWN SEAWEEDS 61 (PHÆOPHYCEÆ) III RED SEAWEEDS 75 (RHODOPHYCEÆ OR FLORIDEÆ) PART II MARINE INVERTEBRATES I PORIFERA (SPONGES) 99 II CŒLENTERATA (POLYPS) 111 III WORMS 159 (PLATYHELMINTHES, NEMATHELMINTHES, ANNULATA) IV MOLLUSCOIDA 187 V ECHINODERMATA 199 VI ARTHROPODA 237 VII MOLLUSCA 299 VIII CHORDATA 471 INDEX 479 INTRODUCTION