UNIVALVES PATELLA. 185 



able in the P. equestris, P. sinensis, and P. duplicata ; 

 these are commonly designated Cup-and-saucer Lim- 

 pets. 



The last division has a very peculiar character, the 

 interior being* furnished with a transverse partition, 

 giving the shell the appearance of a slipper; the P. ne- 

 ritoidea, P.porcellana, and P. fornicata resemble Nerites. 

 The rarest shells of this genus are the P. persona- 

 ta, P. trochiformis, P. mytiliformis, and P. macro- 

 schisma. 



The Limpets are usually found adhering by their base 

 to rocks, stones, fuci, and other marine substances, from 

 which they are not easily detached. They inhabit 

 the Indian, Southern, European, Northern, and Medi- 

 terranean seas, the American and Indian Islands, 

 the Atlantic, and the shores of China, Greenland, and 

 Iceland. 



The Patellae derive their name from their resemblance 

 to a little dish or bason (Patella). 



Division 1. — Shell with the summit obtuse, and the margin entire. 



Scientific Name. Locality. Common Name. 

 Pcllucida Britain, Norway, Medi- 

 terranean Pellucid Limpet • 



Lsevis England, Northern Ocean Smooth • • • do • • 



Radians New Zealand, Terra del 



Fuego Grey-mottled do 



Rota E. & W. Indies Roundish • • do • • 



Testudinaria Norway, East Indies Tortoise-shell do • 



Clealantii Bangor, Ireland Clealand's • do • • 



Testudinalis ••• Norway, St. Domingo •• Small tortoise-sheU 



