CHAP. Ill BIRDS, RATS, AND LIMPETS 57 



thousands of limpets in the course of a single year. Eats are 

 exceedingly fond of limpets, whose shells are frequently found in 

 heaps at the mouth of rat holes, especially where a cliff shelves 

 gradually towards a rocky shore. A rat jerks the limpet off with 

 a sudden movement of his powerful jaw, and, judging from the 

 size of the empty shells about the holes, has no difficulty in 

 dislodging the largest specimens. ' I once landed,' relates a 

 shepherd to Mr. W. Anderson Smith,^ 'on the I. of Dun- 

 staffnage to cut grass, and it was so full of rats that I was afraid 

 to go on ; and the grass was so full of limpets that I could 

 scarcely use the scythe, and had to keep sharpening it all the 

 time.' Sometimes, however, the limpet gets the better both of 

 bird and beast. The same writer mentions the case of a rat 

 being caught by the lip by a limpet shell, which it was trying 

 to dislodge. A workman once observed^ a bird on Plymouth 

 breakwater fluttering in rather an extraordinary manner, and, on 

 going to the spot, found that a ring dotterel had somehow got 

 its toe under a limpet, which, in closing instantly to the rock, 

 held it fast. Similar cases of the capture of ducks by powerful 

 bivalves are not uncommon, and it is said that on some parts of 

 the American coasts, where clams abound, it is impossible to keep 

 ducks at all,^ for they are sure to be caught by the molluscs and 

 drowned by the rising tide. 



The Weekly Bulletin of San Francisco, 17th May 1893, con- 

 tains an account of the trapping of a coyote, or prairie wolf, 

 at Punta Banda, San Diego Co., by a Haliotis Cracherodii. The 

 coyote had evidently been hunting for a fish breakfast, and 

 finding the Haliotis partially clinging to the rock, had inserted 

 his muzzle underneath to detach it, when the Haliotis instantly 

 closed down upon him and kept him fast prisoner. 



Eats devour the ponderous Uniones of North America. When 

 Unio moves, the foot projects half an inch or more beyond the 

 valves. If, when in this condition, the valves are tightly pinched, 

 the foot is caught, and if the pinching is continued the animal 

 becomes paralysed and unable to make use of the adductor 

 muscles, and consequently flies open even if the pressure is 

 relaxed. The musk-rat {Fiber zibethicus) seizes the Unio in his 

 jaws, and by the time he reaches his hole, the Unio is ready to 



^ Loch Creran, p. 102. - Cordeaiix, Zoologist, 1873, p. 3396. 



^ Amer. Nat. -xii. p. 695 ; Science Gossip, 1865, p. 79. 



