8 The N.Z. Journal of Science and Technology. [Jan. 
to the north of Auckland ; the sap-wood is at once attacked by Teredo , 
but the heart is not badly touched, though none of it is free from destruc¬ 
tion by Limnoria and Chelura (see fig. 7). Since 1908, owing to the good 
reports from Sydney (New South Wales) and other harbours as to its 
Teredo-resisting properties, turpentine fender piles only have been used, 
and with satisfactory results ; the Limnoria and Chelura have attacked 
them to a small extent, but there are very few Teredo bores. 
Mr. Hamer notes that the Limnoria and Chelura appear to be more 
destructive now than the Teredo ; that the destruction takes place generally 
between high- and low-water, neap tides (see figs. 8 and 9); that the 
timber below mud-level remains as sound as originally (see fig. 10) ; and 
that no material difference in the destruction of timber by marine pests 
was noted at the outfalls of sewers. 
Fig. 7. —Cross-sections of two totara piles (each 14 in. square), showing destruction 
by Limnoria lignorum and Chelura terebrans. Piles were driven in 1896, and 
these sections measured in February, 1917. Shaded portion shows area re¬ 
maining ; white, area destroyed. (After Hamer.) 
The only fresh water entering the harbour is from storm-water over¬ 
flows and from natural surface drainage, the harbour being entirely an 
estuary and the fresh water almost negligible. 
In consequence of the destruction of timber caused by these marine 
pests the wharves, &c., are now built almost entirely of concrete and 
reinforced concrete, which are not attacked by any of the marine animals. 
Limnoria lignorum is also common in Lyttelton Harbour, where it has 
done a certain amount of damage. In this case it appears to be unaccom¬ 
panied by Chelura terebrans. Mr. Cyrus J. R. Williams, Engineer to the 
Lyttelton Harbour Board, tells me that in Lyttelton it can hardly be called 
a borer, as it seems to operate only on the surface, removing about 1 in. 
from the outside of an ironbark pile in about thirty years, though in softer 
timber its operations are much more rapid. 
Limnoria attacking Submarine Cables. 
The gribble, however, does not confine its attention to timber. In 
March, 1916, I received from Mr. Harold Hamilton, of the Dominion 
Museum, a piece of guttapercha covering the inner core of the Cook Strait 
