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- 



