70 THE LIFE OF THE MOLLUSCA 
six small fish, each nearly as long as their collapsed 
captor. 
Among Pulmonates the most remarkable carnivores 
are the Worm-eating Slugs (Testacella), which follow 
their prey underground. Their method of feeding is 
peculiar, for on coming in contact with a Worm the 
radula is shot suddenly out, and the victim, thus im- 
paled on the barbed teeth thereof, is drawn slowly 
and irresistibly into the Slug’s mouth and gradually 
swallowed (Plate XIV.). Other members of the 
group to which Testacella belongs, such as Oleacina, 
Natalina, as well as some species of Polita and 
Rumina decollata (Plate XIII., Fig. 24), are essen- 
tially carnivorous, feeding mostly on other Snails. 
The ocean-dwelling Cuttlefishes and Argonauta 
are the most rapacious of molluscs, pursuing and 
devouring fish, while the Octopus from his lair in 
the rocks will reach out a long arm and capture fish 
or crabs for his meal, and the Nautilus will take any 
kind of animal bait. 
Of external physical conditions the one most 
affecting the Mollusca is the presence of moisture. 
Without that, existence is for them impossible. 
Even the Desert Snails cannot support life without 
occasional refreshing showers, or moisture in the 
shape of dew. A smart shower after a dry period 
will bring the terrestrial Snails out in such numbers 
from their hiding-places at the roots of grass and 
plants as to give rise to the belief that they some- 
