MONODONTA SUBROSTRATA (Plate VI.).—Fig. 11 is a yellowish shell, about half an inch across, and is usually found near half-tide mark in harbours. The exterior is covered with black or bluish irregular bands. The interior is nacreous, and of a greenish colour, with a white patch round the columella.
MONODONTA AETHIOPS (Plate VI.).—Fig. 12 is a purplish-black shell, tesselated with white between the grooves. These grooves look like lines in the plate. The interior of the mouth is white. Besides being usually covered with vegetable growth, part of which is seen in the illustration, the point of the spire is frequently worm-eaten and defective. This is the usual state in which all shellfish that herd together are found. It is upwards of an inch across, and found in large numbers amongst rocks, especially at the entrance to harbours, and from half-tide mark downwards.
MONODONTA NIGERRIMA (Plate VI.).—Fig. 13 has a smooth, purplish-black exterior, sometimes with small blue spots. The interior is white, and the shell about half an inch across.
MONODONTA LUGUBRIS (Plate VI.).—Fig. 14 is a thick, solid black shell, sometimes over half an inch across, and covered with coarse, irregular granules. The interior is white. This shell is found in large numbers under stones, at the entrances to harbours and sheltered beaches, almost up to high water mark.
There are six or seven other Monodonta in New Zealand, but they are small, and the four above described are the ones most likely to be met with.
TURBO GRANOSUS (Plate VI.).—Fig. 15 is a reddish-purple shell, varied with white, and is sometimes over 2-1/2 inches across. The specimen photographed was much below the average size. The exterior is covered with well-defined rows of granules, while the interior is iridescent. It is found on rocks in the open sea in both Islands, but is a rare shell. The operculum is white and shelly.
TURBO HELICINUS (Plate VI.).—Figs. 16 and 17 (late Turbo smaragdus) is a blackish-green shell, found in great numbers at half tide mark on rocks all over New Zealand, especially at the entrance to harbours and in sheltered bays. Some are as much as 2-1/2 inches across. The inside is white and glistening. The operculum is a solid, round, shelly one, with a greenish centre. In some specimens the outer side of the whorl, instead of being round and smooth, has two or three prominent raised ribs or bands on it. This variety is called Tricostata, and is represented by Fig. 16. I am inclined to believe it is only the young form of the ordinary variety. The Maori name is Ata marama.
ASTRALIUM SULCATUM (Plate VI.).—Fig. 18 (late Cookia sulcata) is a pinkish-brown shell, sometimes over 3-1/2 inches wide. The interior is pearly, and the operculum is shelly, solid, and white. The laminae which cover the shell are easily bleached off, and when the shell is cleaned it has a handsome appearance. It is found in considerable numbers at low water mark amongst rocks on exposed beaches all over the North Island. The Maori name is Kakara or Kaeo, both of which names are also given to the Purpura haustrum (Plate II., Fig. 11).
ASTRALIUM HELIOTROPIUM (Plate VI.).—Fig. 19 is generally known as the circular-saw shell, and, although found all over New Zealand, is comparatively rare. It is reddish-purple, with an iridescent interior, and is sometimes over four inches in width. The shells on the plate are adults. The spines of the younger shells are much longer than those of adults. The best specimens have been dredged by oyster boats.
Plate VII.—Figs. 1 and 2 are Janthina, or violet shells, representatives of which are found all over the warmer parts of the world. The Janthinae live in great numbers on the surface of the ocean, being unable to sink, and are swept by gales and currents in every direction. At intervals, after very heavy gales, they come ashore in the Northern part of New Zealand in cart-loads; but after any ordinary gale a few specimens can be procured amongst the grass cast up by the highest waves. The animal, when touched, emits a quantity of violet-coloured fluid, the same colour as the shell. The shells are very light and fragile. A singular provision for its eggs is found attached to the female Janthina, in the shape of a float, or raft, to the under surface of which the eggs in little bags or capsules are attached, and there they remain until hatched.