PROCEEDINGS OF SECTION D. | 241 
THE MOLLUSCA. 
- Active for evil though the Sphaeroma and other boring crus- 
tacea may be, their depredations are insignificant beside the 
secret and enormous damage inflicted by the shipworms. 
There are several popular notices of the shipworm in books on 
Australian travel. One of the earliest and most interesting is 
the following entrv in the diary of Mr. J. Backhouse, under date 
(th April, 1836, Brisbane, Queensland :—“ One of the young men 
of the company told us that, on a certain occasion when lost in 
the bush, he was driven by hunger to eat a species of Z’eredo, or 
Auger worm, called by the blacks Cobra, which he found very 
palatable. In this part of the country, within reach of the salt 
water, this animal is abundant in logs, which it perforates, till 
they resemble honeycomb (7).” 
GENERAL ASPECT. 
The shipworms are regarded as the most highly modified of 
the whole order of bivalve mollusca. Their general aspect. is 
shown by the figure of Vausitoria thoracites, a common tropical 
species, on Plate VIII. At the broader end is seen a globe with a 
large opening, like a diver’s helmet. This is the bivalve shell, 
through the aperture of which protrudes the muscular, con- 
tracted, pestle-shaped foot, raised in a ring round the edge. In 
life this, the instrument of perforation, is capable of considerable 
protrusion and movement. This is the end which lies in the 
deepest or farthest portion of the burrow. Upwards from the 
shell the long worm-like body tapers towards the small end. It 
is pale pink or yellow, soft, and semi-transparent, showing the 
contained viscera through its walls. There may be traced the 
gills, the stomach, and the intestines. From the smaller end 
protrude two shelly projections, the pallets, which afford the 
best means of distinguishing the different kinds. 
Between these two pallets lie two conjoined tubes, the siphons, 
as they are technically called, which play a most important part 
in the economy of the animal. Through one, the inhalant 
siphon, water is constantly sucked in, and through the other 
regularly expelled. By pouring a little colouring matter into 
the water the current entering one and leaving the other may be 
rendered visible. With the water used for respiration the food of 
the animal, consisting of minute floating animalculae and algae, 
is drawn in. Through the exhalant siphon are expelled the water 
exhausted by respiration, the faeces, wood pulp from the exca- 
vation and the genital products. When alarmed, the siphons 
shrink down the burrow, the pallets then close over them and 
(7) Backhouse. Narrative Visit Australian Colonies, 1843, p. 365. 
Q 
