212 POPULAR CONCHOLOGY. 



an umbilicus ; operculum generally horny, thin, 

 and spiral, with many whorls. Animal, head 



distinct, having two tentacula with eyes at the 

 base; foot short and round. — There are 69 



This genus is distributed all over the world, 

 and presents a great many species. The Tro- 

 chus agglutinans* , from the Antilles, is remark- 

 able for the singular habit of accumulating, 

 during its formation, different substances which 

 adhere to its shell. It is often found covered 

 with stones, corals, small shells, and fragments 

 of all kinds, and on account of this curious pro- 

 pensity it has been named the Carrier : it is sup- 

 posed that it does this for the purpose of strength- 

 ening its shell, which is very thin and brittle, 

 and that it causes the substances it collects to 



* This species of Trochas has been formed into a genus 

 by Montfort, and called Phorus. 



species recent, 9 fossil. 



