252 PROCEEDINGS OF SECTION D. 
longest shipworm does not necessarily bore a hole of the greatest 
diameter. Three-quarters of an inch is the usual diameter for 
the burrows of VV. edaz, but as the type of that shell exceeds an 
inch in breadth, such a diameter cannot be regarded as of the lar- 
gest calibre. The largest foreign records of length of animal 
and diameter of hole appear to be 4 ft. and 14 in. respectively. 
Unfortunately, the species furnishing these measurements are 
not mentioned by name (e). 
To the destruction of wharves, bridges, and shipping is to be 
added the damage done to submarine cables. Coppinger writes : 
“There are now two submarine cables connecting Port Darwin 
with Singapore, vid Java, and thence with Europe. The first 
was laid in 1872, and was found most difficult to maintain on 
account of the ravages made in it by a boring mollusc, a species 
of Zeredo, which, in an amazingly short space of time, pierced 
the galvanised iron wire sheathing of the cable and destroyed the 
insulation of the copper core. The repairs of this cable necessi- 
tated an outlay of £20,000 per annum, a circumstance con- 
trasting strangely with the condition of a similar cable in the 
India and China seas, which is not attacked by the Teredo. 
Recently a duplicate cable has been laid, in the construction of 
which a tape of muntz metal was wound round in a spiral fashion 
between the insulating material and the twisted wire sheathing. 
By this provision the new cable has been rendered proof against 
the boring effects of the Z'’eredo, and has hitherto worked success- 
fully without the slightest hitch (/). 
REMEDIES. 
Remedies may be divided into natural and artificial. One 
natural agent has been mentioned in a preceding section dealing 
with Life History, as the Vereis, a carnivorous Annelid, whose 
larve preys on the living shipworm. Another natural agent 
which, as it is inapplicable to our latitudes, deserves but brief 
mention, is cold. A severe frost coinciding with a low tide has 
been observed in Holland to effect a wholesale destruction of 
Teredo. A dense sheath of living sessile cirripedes might afford 
a natural protection, if they could be induced to grow where re- 
quired. The natural agent of most service in Australia is mud. 
Water fouled by mud or sewerage is obnoxious, or even fatal, to 
the Cobra. Mr. J. Booth related to a Parliamentary Committee 
the following instances of the longevity of certain piles :—*“ This 
is a sample, as far as I can glean, of the old King’s Wharf. A 
gentleman who does not live far from here went, in 1821, with 
Mr. Hutchinson, Colonel Grimwood, and Major Druitt to survey 
and report upon the old King’s Wharf. The piles were driven in 
1801, and in 1821 they reported that the Cobra was only in 
(¢) Snow. Op. cit., p. 410, Pl. xxvi. 
(7) Coppinger. Cruise of the Alert, 1883, p. 202. 
