Among the small animalcules of the phylum /Protozoa/ are some which are familiar to all by name, such as the /Infusoria/, which are most interesting creatures to examine in a drop of water under the microscope. A more tangible example of the /Protozoa/ are the /Foraminifera/. /Foraminifera/, like diatoms, have a shell-like covering, and these shells, among the most plentiful of which are those of the genus /Globigerina/, fall, as do those of diatoms, in immense numbers to the bottom of the ocean, and form respectively what are known as /Globigerina/ and diatomaceous ooze. In course of time the sedimentary strata become fossilized; thus, the stone of which the city of Paris is built consists of fossilized [pg022] foraminifers, and the pyramids of Egypt are built of nummulites, another genus of /Foraminifera/. It is estimated that an ounce of this deposit contains four millions of these protozoans, so it is impossible to conceive the numbers of once living animals represented in the tombs of the Pharaohs. Telegraph-cables raised from the depth of two miles bring the message to naturalists that the bottom of the ocean at that depth is composed of little else than the calcareous shells of /Foraminifera/.
Many of the lower animals resemble plants in form. Hydroids and polyzoans are often gathered and preserved as seaweeds. Corals, sea-anemones, and holothurians are curiously like plants. For a time the confusion about the division of animals and plants was partly owing to this resemblance of forms, and the theory of the animal nature of corals was for a long time considered to be refuted by the testimony of a naturalist who declared that he had seen them in bloom. Later this class of animals was believed to occupy an intermediate sphere and partake of the characteristics of both kingdoms. The name zoöphyte, meaning "animal-plant" or "mingled life," was adopted because of these resemblances and was formerly applied to these forms only. To-day it has a broader application. There is still a neutral class, called /Protista/, comprising organisms which have not yet been classified as plants or animals. [pg023]
All living things which inhabit the sea have their appointed boundaries, and the localization of marine life is as distinct as is that of terrestrial life. Each kind of beach has forms of life peculiar to itself. Those animals which inhabit rocky shores or stony beaches or sand or mud may be looked for anywhere under similar physical surroundings. They are, however, modified by climatic conditions, and in wide ranges differ in genera and species. The rocky coast of Maine has a class of sea-urchins and starfishes which are different from those which live on the rocky shores of the northern Pacific coast, yet they are all easily recognized as belonging to the same family, and a description of typical forms is a sufficient guide to the recognition of their relationships.