UNIVALVES. 175 
the feeblest of created beings. The Torpedo, defended 
himself from his enemies by means of an electric 
shock, long before academicians thought of making 
experiments in electricity. The Limpet, acted as if he 
understood the pressure of the atmosphere, and 
attached himself to the rock, by forming a vacuum in 
his pyramidical shell, more than five thousand years 
before the air-pump came into existence! 
Limpets* are generally found adhering by their 
base to rocks and stones, to fuci, and other marine 
substances, from which, as I have before observed, 
they are not easily detached. They are common on 
the shores of every ocean ; but the island of Cyprus 
is particularly celebrated for the beauty and variety 
of its specimens. _ 
Shells of this interesting genus are frequently 
discovered in a fossil state. The Patella mitrata of 
Linneus, and the P. cornucopia and dilatata of Le 
Chev. de Lamar, are each attached with a small 
ligament, or muscle, to an operculum or under- 
valve. By the aid of this singular appendage, they 
not only fix themselves to rocks and marine pebbles, 
but also rise occasionally above them, like sentry 
boxes on an elevated station. 
Little is known with certainty respecting the pecu- 
* Seven divisions are assigned by naturalists to this extensive 
genus, the distinctions of which are strongly marked. 
