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 The broken pile in the foreground of the group with its colonies of mollusks, hydroids, sponges and ascidians.

place in the daily life of every one. The same is true of our terrestrial plants. But while the sea is familiar to us in its outward aspects, while certain of its creatures are well known to us because of their food value or for other reasons, yet the vast majority of the life that crowds that watery atmosphere has been effectually concealed from the generality of mankind by the density of the medium in which it lives. This is true not only of the animals of the deeper waters but of those that people the very margin of the sea as well. Here in the shallows life abounds. Here the struggle for existence is fiercest, and it is here that the closest adaptations to environment may be seen. These ocean margins were doubtless the theater of much of that tremendous evolutionary progress which in Archean times laid down the foundations of the great phyletic groups of the animal kingdom.

In order to give a picture not only of the abundance, variety and beauty