106 Beautiful Shells. 
of the rock are not always sure. ‘The peasantry 
of the western isles of Scotland,” we are told by 
Miss Pratt, “look to the Periwinkles and Limpets, 
which abound on the rocks, for their daily meal, 
often for long seasons subsisting almost entirely 
upon this humble food. In the Isle of Skye, the 
inhabitants are often, at one time of the year, with- 
out any other source of provision.” Then comes the 
Sea-gull, and the Duck, and the Pied Oyster- 
catcher, to feed on the poor little mollusk, the bill 
of the latter bird being admirably adapted for 
loosening its hold on the rock. 
Patella in Latin signifies a salad-dish, a knee- 
pan, and several other domestic utensils, of a broad 
shallow make; and hence we find the plural form 
of the word applied to the Limpet family, whose | 
shells are of such a shape. Members of this family 
are found on all rocky coasts, except those of the 
Arctic seas; on tropical rocks they grow to a large 
size, and form a valuable article of food. A very 
curious piece of mechanism is the tongue of the 
Common Limpet; it is from two to three inches 
long, and has a spoon-like extremity, so that it 
looks, when extended from the mouth, like a small 
snake. If examined through a microscope, it is 
seen to be armed throughout its whole extent with 
