It had flat, long, narrow, and pointed wings because it came gliding swiftly and low, and scraped the sand before its wings were closed. This is shown by the few scratches before the prints became perfect. A certain class of birds thus arrests the impetus of flight. It had a long feeling-bill, as shown by the little holes in the sands where the marks became entangled; and so on. These combined characteristics belong to one class of birds and to no other; so he knows as definitely as [pg005] though he had seen the bird that a sandpiper alighted here for a brief period, for here is his signature.

It is plain that tracks in the sand mean as much to the naturalist as do tracks in the snow to the hunter, and trails on the land to the Indian who follows his course by signs not seen by an untrained eye.

The tide effaces much that is written by foot and wing, but sometimes such signs are preserved and become veritable "footprints on the sands of time." In the Museum of Natural History in New York is a fossil slab, taken from the Triassic sandstone, showing the footprints of a dinosaurian reptile now extinct, which, in that long ago, walked across a beach—an event unimportant enough in itself, but more marvelous than any tale of imagination when recorded for future ages. From such tracks, together with fragments of skeletons, the dinosaur has been made to live again, and its form and structure have been as clearly defined as those of the little sandpiper of Dr. Coues. [pg006]

II
COLLECTING

It has been said that everything on the land has its counterpart in the sea. But all land animals are separate and independent individuals, while many of those of the sea are united into organic associations comprising millions of individuals inseparably connected and many of them interdependent, such as corals, hydroids, etc. These curious communities can be compared only to the vegetation of the land, which many of them resemble in outer form. Other stationary animals, such as oysters and barnacles, which also depend upon floating organisms for their food, have no parallel on the land.

The water is crowded with creatures which prey upon one another, and all are interestingly adapted to their mode of life. Shore species are exceedingly abundant, and the struggle for life is there carried on with unceasing strife. In the endeavor to escape pursuers while they themselves pursue, these animals have various devices of armature and weapons of defense; they have keen vision, rapid motion, and are full of arts and wiles. One of the first resources for safety in this conflict is that of concealment. This is effected not only by actual hiding, but very generally by mimicry in simulating the color of their surroundings, and often by assuming other forms. Thus, for instance, the sea-anemone when expanded looks like a flower and is full of color, but when it contracts becomes so inconspicuous as to be with difficulty distinguished from the rock to which it is attached. Anemones also have stinging threads (nematophores), which they dart out for further defense. [pg007]

The study of biology has great fascination, and the subject seldom fails to awaken interest as soon as the habit of observation is formed. Jellyfishes, hardly more dense than the water and almost as limpid, swimming about with graceful motion, often illuminating the water at night with their phosphorescence, showing sensitiveness, volition, and order in their lives, cannot fail to excite wonder in even the most careless observer. Not less interesting are the thousands of other animals which crowd the shores, lying just beneath the surface of the sand, filling crevices in the rocks, hiding under every projection, or boldly—perhaps timidly, who shall say?—lying in full view, yet so inconspicuous that they are easily passed by unnoticed.

To find these creatures, to study their habits and organization, to consider the wonderful order of nature, leads through delightful paths into the realms of science. But even without scientific study the simple observation of the curious objects which lie at one's feet as one walks along the beach is a delightful pastime.

The features which separate the classes and the orders of both the plant and the animal life are so distinctive that it requires but very superficial observation to know them. It is easy to discriminate between mollusks, echinoderms, and polyps, and to recognize the relationship between univalves and bivalves, sea-urchins and starfishes, sea-anemones and corals. The equally plain distinctions between the branched, unbranched, tubular, and plate-like green algæ make them as easy to separate.

The pleasure of a walk through field or forest is enhanced by knowing something of the trees and flowers, and in the same way a visit to the sea-shore becomes doubly interesting when one has some knowledge, even though it be a very superficial one, of the organisms which inhabit the shore.

ROCKY SHORES

Rocky shores furnish an abundance and great variety of objects to the collector. The seaweeds here find places of attachment, and the lee and crevices of the rocks afford shelter to many animals which could not live in more open and exposed places. The [pg008] rock pools harbor species whose habitat is below low-water mark and which could not otherwise bear the alternation of the tides.

The first objects on the rocky beach to attract attention are the barnacles and rockweeds. They are conspicuous in their profusion, the former incrusting the rocks with their white shells, and the latter forming large beds of vegetation; yet both are likely to be passed by with indifference because of their plentifulness. They are, however, not only interesting in themselves, but associated with them are many organisms which are easily overlooked. The littoral zone is so crowded with life that there is a constant struggle for existence,—even for standing-room, it may be said,—and no class of animals has undisputed possession of any place. Therefore the collector should carefully search any object he gathers for other organisms which may be upon it, under it, or even in it, such as parasites, commensals, and the organisms which hide under it or attach themselves to it for support. Let the rockweed (Fucus) be carefully examined. Among the things likely to be found attached to its fronds are periwinkles (Littorina litorea), which simulate the plant in color, some shells being striped for closer mimicry. Sertularian hydroids also are there, zigzagging over the fronds or forming tufts of delicate horny branches upon them. Small jelly-like masses at the broad divisions of the fronds may be compound ascidians. Calcareous spots here and there may be polyzoans of exquisite form, while spread in incrusting sheets over considerable spaces are other species of Polyzoa. Tiny flat shelly spirals are the worm-cases of Spirorbis. A pocket-lens is essential to enable one to appreciate the beauty of these minute forms. Under the rockweeds are many kinds of crustaceans; perhaps there will also be patches of the pink urn-like egg-capsules of Purpura at the base of the fucus.

Various kinds of seaweed abound in the more sheltered parts of the rocks, and among them will be found amphipods and isopods, many of which are of species different from those of the sandy beaches. Here, too, is the little Caprella, imitating the seaweed in form, and swaying its lengthened body, which is attached to the plant only by its hind