MASEFIELD : THE ECONOMIC USE OF SOME BRITISH MOLLUSCA. l6l 



no doubt game birds feed on H. rufescens and other snails, and we all 

 know how greedily ducks feed on all molluscs and especially fresh- 

 water snails. Then again Ancylus fluviatilis, Physa, and Valvata, form 

 a considerable portion of the food of the Dipper, the Moor Hen, Coot, 

 Water Rail, and the Waders, and fish. The extent to which Thrushes 

 feed on snails is clearly shown by " Thrush stones " (or " Thrushes' 

 altars " as they are called), where these birds break up the shells of 

 snails for the purpose of feeding on the animals therein. The food of 

 the Blindworm (Angi/is fragilis) consists almost exclusively of Agrio- 

 limax agrestis, and this reptile should in consequence be carefully 

 protected, instead of being destroyed as it generally is whenever caught. 

 The frog and other amphibians are also feeders on our small snails 

 and slugs. A few years ago I collected a number of Natterjack 

 Toads (Bnfo calamita) in a wet ditch at Southporr, and placed them 

 in a tin box. The next morning I found they had disgorged a large 

 number of Planorbis spirorbis, which evidently forms their staple food 

 in that locality. 



Huxley tells us that the Crayfish (Astacus) feeds on freshwater 

 mollusca, eating shells and all. Molluscs also form food for the 

 Hedgehog in his nocturnal rambles, and both the Fox and Badger are 

 said to feed on snails and slugs when pressed by hunger. Mr. Adams, 

 in a note in Science Gossip, gives his opinion that wild rabbits feed on 

 Helix nempralis, H. aspersa, and H. itala, from the piles of the shells 

 of these molluscs which he found at the mouths of rabbit burrows on 

 the sand dunes in Ireland, empty and apparently gnawed by the rab- 

 bits. I think it is extremely probable that rabbits do eat these 

 molluscs as a means of obtaining moisture, as these sandhills are 

 entirely destitute of fresh-water or succulent food. 



Anodons when thrown on a bank or left high and dry are a tempt- 

 ing morsel to Rooks and Jackdaws, which easily make a hole in the 

 shells with their beaks and extract the animals. On the table I have 

 placed shells thus pierced by Rooks. Water Voles and Rats, too, feed 

 on these molluscs, as well as Dreissensia, and Mr. Whitlock, in our 

 Journal (vol. 8, p. 205) states that he has found numbers of these shells 

 bitten all round the edges by Otters, and Mr. Harting confirms this, 

 and gives other instances, in his " Rambles in Search of Shells," of 

 Otters feeding on bivalves. Water Shrews find welcome food in the 

 Sphseriidse, and Shrews, Bank and Common Voles feed greedily on 

 all the Zonites and young Helices, as collectors well know from the 

 disappointment they so often experience in turning over a promising 

 stone or log of wood, only to find the ground underneath traversed 

 by the runs of these little mammals, and littered with the broken 

 shells of the molluscs being sought for, 



