Sea Shells 
of New Zealand 
Plate X 
No. 15 
Plate X 
No. 13 
, 
epidermis 1s somewhat shiny and turned in or reflected 
at the margin, giving a narrow and very vivid grass-green 
or dark-brown edging to the interior. Inside, the shell is 
purplish white and iridescent. Large shells may be as 
much as six or even eight inches in length. These mussels, 
when dredged from deep water, are thin and pale in colour, 
while those from the litoral zone (between tide marks) 
and just below low-water mark are much thicker and 
heavier in build, besides being considerably darker in col- 
our. The increase in colour is due to the greater amount 
of light they receive, and the extra thickness is a provision 
of nature to enable the shells to withstand the full force 
of the breakers. 
Throughout New Zealand. Mount Maunganui. It is 
also found on the Tasmanian coast. 
MYTILUS PLANULATUS (mytilus, Green name for 
sea mussel; planus, smooth; lJatus, wide).—Smaller than 
the M. canaliculus or Horse mussel, though similar in shape 
and greatly superior to that species, both in delicacy of 
flavour and tenderness. Regarding the shell, it differs 
mostly in the number of teeth at the hinge, and in the 
colour. It is of a blackish blue, brown towards the hinges, 
and internally bluish white, and not iridescent, as is the 
case in most of the other mussels. The colour deepens 
towards the margin, and at the extreme edge there is a 
narrow black polished band. It is about three inches long, 
as a rule, but may be as much as three and three-quarter 
inches. Specimens from the Bay of Islands are short and 
broad, with a very pronounced curve. This mussel, until 
quite recently, was supposed to be exactly the same species 
as M. edulis, or the true edible mussel which is in such 
demand in the North of England, where tons of them are 
annually consumed. It is found throughout New Zealand, 
but is more common in the South Island. 
Great Barrier Island; Auckland and Campbell Islands. 
MYTILUS MAGELLANICUS (mytilus, Greek for sea 
mussel; Magellan, the navigator) —A mussel which can 
be readily identified by the sculpturing of strongly-marked 
ribs, some of them bifurcating, extending from the beaks 
to the margins. The valves are much thicker and stronger 
than we find in the case of any of the other mussels, and 
the beaks are sharply pointed, long and narrow from side 
to side. The colour is black or purplish maroon, the beaks 
white. Young shells are of a light brown colour. The 
interior is white or very pale purple, and is slightly irides- 
cent. It is about three inches in length, and is found 
88 
