CHAPTER III.
DESCRIPTION OF PLATES.
Amongst the best known shells in any part of the world the Nautilus takes a leading position. Named Argonauta by scientific men, after the Argonautae, or sailors of the Argo, it has been the subject of many legends from the earliest times. Aristotle describes it as floating on the surface of the sea in fine weather, and holding out its sail-shaped arms to the breeze. This is now known to be incorrect, as the use it makes of these arms is to help it in swimming through the water. New Zealand’s specimen, the Argonauta nodosa, also known as Argonauta argo, the most beautiful of the four known species, is depicted on Plate I. Being a floating shell, and found even hundreds of miles from land, our Nautilus is not peculiar to New Zealand. Its beautiful white, horny-looking shell can be obtained from most parts of the Pacific and Indian Oceans, but in no part of the world can finer specimens than ours be found. It is known to the Maoris as Muheke or Ngu, and colloquially as the Paper Nautilus.
The animal that produces this shell belongs to the octopus, or cuttlefish, family. The male is an insignificant-looking octopus, about an inch Iong. The female grows many times larger, as can be imagined from a glance at the shell in the plate, which measured nine inches across, and was found at Mayor Island, in the Bay of Plenty, and is now in the possession of Mr. C. Spencer.
In the shell the female lays her eggs, and in it the young are hatched. Unlike all other shells, the Nautilus is not moulded on the animal, nor is she even attached to her shell by muscles. When washed ashore she can wriggle out of her shell and swim away. In her shell she lies as in a boat, propelling herself by slowly sucking up water, and violently ejecting it through a funnel, or syphon, at the same time using her arms as oars, to increase her speed. Dame Nautilus can sink to the bottom of the sea if she chooses; and when wishing to crawl about the sand or rocks she turns over and carries her shell on her back, like a snail.
