Sea Shells 
of New Zealand 
Plate XII 
No. 12 
with the dorsal border, which is quite straight. The hinge 
is at the posterior end of the shell, causing it to be very 
asymmetrical. The anterior end is rounded and flattened, 
like the thin end of a wedge, from which the strong, tri- 
angular, and fleshy foot protrudes. The interior is smooth 
and porcellanous. ‘The largest specimens are about two 
and three-quarter inches in length. Sometimes they may 
be seen rapidly digging themselves into the sand on ocean 
beaches as the tide comes in, this manceuvre being accom- 
plished by means of the powerful foot. When the animals 
are buried a little beneath the surface of the sand, and 
are washed by the incoming tide, the tips of the siphons 
can be seen just exposed, the larger one with a kind of 
fringed extremity, being that by which the animal draws 
in water whence it obtains its food, and the small plain one 
that by which the waste water is expelled. Although this 
mollusc is commonly known as the Pipi by Europeans, 
especially fishermen, it is not the pipi of the Maori, that 
name being used by them to denote the M. Australis, as 
well as the Chione Stutchburyi. The native name for the 
M. subtriangulatum is Tuatua and Kahitua. 
Found in both Islands. Mount Maunganui; Chatham 
Islands. 
MESODESMA VENTRICOSUM (meso, middle; desma, 
a ligament; ventricosum, swelled out).—This is the well- 
known Toheroa, a large thick, solidly-built bivalve of a 
somewhat dingy greyish or yellowish-white colour, wedge- 
shaped, being thin at the anterior end, which is evenly 
rounded in outline. The beaks are close together and 
near to the posterior end. Sculpture consists of irregu- 
larly sized and spaced concentric striations, more pro- 
nounced at the ventral margin and at both ends, and ex- 
ceedingly fine and inconspicuous radiate striations. Usu- 
ally about four or five inches in length; specimens have 
been recorded of seven inches. At first sight the resem- 
blance between the Toheroa and the M. subtriangulatum 
is remarkable, so much so that specimens of one and a-half 
inches of both species may be easily confounded by the 
uninitiated. You must observe, however, that the Toheroa, 
size for size, is considerably the thinner and lighter of the 
two, although both are technically described as solid shells. 
The Toheroa is, moreover, slightly wider at the anterior 
or thin end; the ventral or lower border is more distinctly 
curved, and that portion of the valve just below the beaks 
is more swelled out—hence the name, ventricosum. On 
examining the interior of the shell, a hollowed-out spoon- 
like process is to be seen, one in each valve, close to the 
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