Sea Shells 
of New Zealand 
Plate X 
No. 4 
Plate X 
No. 7 
substance, and by the side of its near relative, the Rock 
oyster, amply bears out Shakespeare’s ideas about compari- 
sons. It has a rounded shell, the right valve flat, the left 
valve hollowed out for the animal’s body. Sculpture con- 
sists of concentric laminations on the flat valve, the deep 
valve having also a number of short, rounded ribs at the 
ventral margin. The hinge plate is triangular, and there 
are no teeth. The interior is of a pale greyish white, 
blending with greyish green, slightly pearly and iridescent. 
About three and a-quarter inches long by two and three- 
quarter inches across. 
North and South Islands. Mount Maunganui; Foveaux 
Straight; Stewart Island. | 
OSTREA GLOMERATA (ostrea, an oyster; glomer- 
ata, aggregated or massed together ).—This is a case where 
one might be excused for saying it is too well known to 
need description, but it is as well to describe a few out- 
standing features which make it easy to distinguish from 
the other members of the oyster family. The two valves 
are right and left; the right being the uppermost one, 
which is concentrically laminated, or perhaps it would be 
better understood were we to say the valve is composed of 
more or less rounded plates of diminishing size placed one 
above the other in a rather irregular fashion. It is gener- 
ally fairly flat, and the margin is toother or frilled with 
purplish-black projections fitting very closely into corres- 
ponding wavy scallops on the left valve. The left valve 
is deeply hollowed out and firmly cemented to the rock, or 
shell of another oyster. The hinge is rather square, and 
flattened, with a row of granular teeth extending on either 
side, nearly half-way towards the ventral margin. The 
interior is greenish white, marked with blackish purple at 
the border, slightly pearly, and there is one muscle scar in 
each valve situated towards the posterior end of the shell. 
To determine the ends of the shell, hold the flat valve in 
the right hand and the deep one in the left, with the hinges 
pointing towards each other, the internal surfaces upper- 
most. The anterior end is nearer to you, the posterior end 
further away. 
Northern parts of New Zealand. Hauraki Gulf; Bay 
of Islands; Mount Maunganui. 
ATRINA ZELANDICA (atrina, dim. of ater, atra, 
black, a dismal black, in contra-distinction to niger, a glossy 
black).—The Fan mussel. A long, large, wedge-shaped, 
fragile bivalve, the anterior end coming fo an acute point, 
the posterior end somewhat rounded and wide. The dorsal 
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