MOLLUSCA OR UNIVALVES. 213 



adhere to it by bringing its shell into contact 

 with them whilst the shelly matter is still in a 

 partially liquid state. Mr. Swainson mentions* 

 that amongst some fresh-water shells he received 

 from Brazil he found two small ones resembling 

 a Helix, and was led to examine them, 

 as their outside was covered with 

 particles of dirt and sand. On 

 placing them, however, under the 

 magnifier, he was surprised to find 

 that the shells were actually composed of little 

 stones and grains of sand only, agglutinated 

 together with so much skill by the animal, that 

 the regular turns of the spire and the form of 

 the umbilicus were most accurately preserved. 

 They were, in short, fresh-water Carriers. The 

 Trochus longispina, from India, has the circum- 

 ference ornamented by a row of long spines, of 

 a silvery or gold colour, placed at regular dis- 

 tances, and somewhat resembling the rays of 

 the sun as they are represented in carved work ; 

 the shell itself is also of a golden colour. The 

 Trochus jujubinus, found in the seas of the Isle 

 of France, is remarkable for its peculiar colour- 



* Treatise on Shells and Shell-Fish. 



p 3 



