The Raised Beaches of New Zealand contain numerous marine shells all having living representatives. Some of these elevated beaches occur as high as 150 feet above sea-level at Taranaki, and at 200 feet near Cape Palliser in Cook Strait.
Many species of Pleistocene Mollusca identical with those now living in Torres Strait, the China Sea and the Philippine Islands are found in Papua. They occur in the greenish sandy clay of the hills near the present coast line and comprise the following genera of Gasteropods:—Ranella, Nassa, Mitra, Oliva, Terebra, Conus, Strombus, Bulla and Atys.
Characters of Cephalopoda.—
The highest class of the mollusca is the CEPHALOPODA (“head-feet”). In these shell-fish the extremity of the body or foot is modified, and furnished with eyes, a funnel and tentacles. It has also strong horny beaks or jaws which make it a formidable enemy to the surrounding life in the sea. In the chambered forms of this group the animal partitions off its shell at regular intervals, like the Pearly Nautilus and the Ammonite, inhabiting only the last chamber cavity, but still communicating with the earlier series by a continuous spiral tube (siphuncle). In some forms like the living squid and the extinct Belemnite, the shell is internal and either spoon-shaped, or dart-shaped, that is, subcylindrical and pointed.
Characters of Cephalopod Shells.—Nautiloidea.—
In geological times the nautiloid forms were the first to appear (in the Ordovician), and they were either straight shells, as Orthoceras, or only slightly curved, as Cyrtoceras. Later on they became more closely coiled, and as they were thus less likely to be damaged, they gradually replaced the straight forms.
The Ammonites have the siphuncle close to the outside of the shell, whilst in the Nautilus it is more or less median. The sutures or edges of the septa in Nautilus and its allies are curved or wavy, but not so sharply flexed or foliaceous as in Ammonites. The Nautiloidea range from the Ordovician and are still found living.
Ammonoidea.—
The Ammonoidea appear in Devonian times and die out in the Cretaceous. They were very abundant in Jurassic times, especially in Europe.
Belemnoidea.—