144 THE LIFE OF THE MOLLUSCA 
frequently the cause of poisoning when eaten. 
Limnea truncatula, as already stated (ante, p. 79), 
is the intermediate host of the Liver Fluke of Sheep. 
The mischief that Slugs and Snails can work to 
crops and in gardens is only too well known; the 
former are also said to damage corks. 
The amount of mischief that has been caused by 
the Ship-worm (Teredo) is almost incalculable, but 
with the passing of the wooden ship and the ex- 
tensive use of iron and steel work for piers, its 
destructive energies are now mainly confined to 
the timber work of groynes and landing-stages. 
There it is still the despair of the engineer, for no 
known method of treating the piles will keep the foe 
at bay. 
The prices paid by collectors for fine specimens of 
rare shells, although at one time considered high, 
are insignificant beside those given of late years for 
scarce postage stamps. Thus £43 10s. was paid in 
1854 for a Conus gloriamaris, and £42 in 1865 for 
another example. The latter figure was also realized 
the following year for a specimen of Cyprea guttata, 
and £40 for a C. princeps, while as much as £100 is 
said to have been given for a single specimen of the 
heteropod Carinaria, now worth only from £5 to 
£10. Of late years the highest sum paid for a single 
shell was that given for the magnificent Pleuvotomaria 
Adansoniana, now in the Natural History Museum, 
for which the original vendor obtained £55. 
