154 



POPULAR CONCHOLOGY. 



similar substances, with which the larger shells are abun- 

 dantly covered.* 



There are other species, on the contrary, which do not 

 remain entirely attached to the same place, but occasionally 

 move ; and others, again, which fix themselves to sea- 

 weeds, which appear to be the food of the whole genus. 

 They are particularly abundant at the Island of Cyprus 

 and the Cape of Good Hope ; where they are often found 

 of a very large size, and are used as spoons by the Hot- 

 tentots. The common English species is rather smooth 

 on the outside ; but many of the foreign ones are covered 

 with ridges in rays from the apex to the circumference. 

 Sometimes these ridges extend beyond the edge of the 

 margin, and appear like the rays of a star. Some species 

 were used for the table in former times, and the common 

 species of the British coasts is still gathered by the poorer 

 people for the same purpose. 



Philippi mentions Nacella Schum. ; Helcion Montf. ; 

 and Scutellina of Gray, as sub-genera. 



Carinaropsis. Hall. — Shell symmetrical, almost co- 

 nical, patella-formed, somewhat angular, or keeled at the 

 back ; the aperture oval, contracted behind. — Fossil. 



Family 2. — CHIT ON A CEA. 



The animals have no tentacula, and no eyes, and the 

 heart is placed behind. The shell is formed of eight small 

 pieces, lying one over the other in a row, united by a 

 tough ligament. — Marine. 



Chiton. Lin. — Shell oblong, composed of about eight 

 pieces, which fold over each other at their edges, and are 



* Gray, Philosophical Transactions, 1833. 



