and varied as to defy all comparison or description. These little animals, living in the water and moving from place to place, are as perfect and sea-worthy ships in miniature as the best modern vessels, and built upon as improved a pattern as our vessels which have been so long evolving. They have for centuries plowed the open seas in their vessels, never seeking port and never suffering disaster. With their air-float above, in addition to buoyancy, perfect stability is obtained. Their body below serves as ballast, and their membranous wings are good sails, that can be furled or hoisted at the animal's will. No masts to be carried away, no anchor needed, but perfect safety always. How well adapted for their surroundings—indeed, how well all Nature's creatures are adapted for their mode of life! How many ideas in modern architecture and engineering, but just discovered as the result of long study and experiment, have been in use for centuries untold among the lower animals which we are so wont to regard as unworthy of life! The ant, the bee, the spider, and hundreds of others are to-day using principles which man has yet to learn. The properties of the arch and dome, if not first learned from animals, might have been, much to man's advantage, long before he discovered them.
On very rare occasions the nautilus is found, and at times we also fall in with the Argonauta, or paper nautilus. They are both related to cuttle-fishes, differing from them in having shelly coverings and in some other more technical points. Each has a row of arms, with suckers around the mouth, and they move in the same manner as true cuttle-fishes do—by ejecting a quantity of water through a tube with such force as to drive the animal backward. The nautilus, as it grows, builds the shell larger to accommodate the growing body, building on the edge and continuing the spiral, and at the same time forming a partition across the rear. If a nautilus-shell is cut longitudinally, it will be found to be made up of a large anterior chamber, which the animal occupied just before it died, and behind a large number of chambers separated from each other by transverse partitions, and connected together only by a small circular hole that exists in each partition. When the nautilus is alive, a fleshy tube runs through all these chambers, passing through the holes, and forms the only connection between the animal and the rear chambers once inhabited by it. It is thought that by means of this tube the rear compartments can be filled with water or emptied at the animal's will, thus allowing it either to rise to the surface or to sink to any required depth. Argonauta is a pure white, ridged shell, thin and delicate, the animal being very much like the nautilus; but in this case the female alone has the covering, while the male is entirely without a shell. In many cases, among the lower forms of ani-