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MYTILUS MAGELLANICUS (Plate X.).—Fig. 6 is a bluish mussel, with prominent ribs, as shown in the plate. The interior is white, and the shell is found up to three inches in length.
VOLSELLA AUSTRALIS (Plate X.).—Fig. 7 (late Modiola australis) is a rough-looking, uneven shell, of a pale chestnut colour. It usually has a hairy-looking growth near the edge, as shown in the plate. It is found up to four inches in length.
There are two other of the Volsella family in New Zealand, neither of which are illustrated. The Volsella fluviatilis, a shiny, black mussel, shaped like the Edulis, and about 1½ inches long, found in brackish water, is the most common. The inside is bluish-white, and purplish round the margin.
OSTREA ANGASI (Plate X.).—Fig. 8 is a mud oyster, of which those dredged at Stewart’s Island are the largest we have. Fine specimens were found in Ohiwa Harbour prior to the Tarawera eruption of 1886, but the deposit from that eruption appears for the time being to have destroyed them. There must be some large banks of this oyster in the Bay of Plenty, judging by the number of dead shells washed up in places; but, although I many times used the dredge while in Tauranga, I never had the good fortune to find one of the banks. Cartloads of the shells were at times washed up on the beach between the town of Tauranga and the entrance to the harbour.
The best known oyster in New Zealand is the Auckland rock oyster, the Ostrea glomerata (not shown in the plate), which is familiar to all who visit the seashore in the North. The Maori name for the rock oyster is Tio, and for the mud oyster Tiopara.
PLACUNANOMIA ZELANDICA (Plate X.).—Fig. 9 is of the family known in England as the pepper and salt oyster. The lower valve is fiat and has the large oval opening, shown in the plate, through which the foot of the animal protrudes and holds the shell on to the rock. The shell is thin and fragile, and is found in both Islands. Another shell of the same family, the Anomia walteri (not shown on plate), is found at the Bay of Islands, and is usually coloured bright yellow or orange.
MUREX RAMOSUS, the last figure, is the latest addition to our New Zealand marine shells, and is described with the others of the Murex family on Plate II., and on page 16.
