SHELLS AND MOLLUSCOUS ANIMALS. 221 



pounds ; but the shell, though beautiful, was 

 prized chiefly because it was rare, and now that 

 plenty can be obtained, a few shillings will suffice 

 for its purchase. 



There is a shell lying about most of our beaches 

 and sandy shores, commonly called the Sea Snail- 

 shell (Natica monolifera}. It is shaped like that 

 of the garden snail, but highly 

 polished, and of a bright brown 

 colour marked with darker 

 streaks. The eggs of the Na- 

 tica are most singular. They 

 resemble thin cakes of biscuit 

 several inches in diameter, 

 which, if held up to the light, 

 seem composed of a number of cells covered with 

 sand. 



Still more like our garden snails in the form and 

 brittle texture of its shell, is the beautiful and 

 fragile Oceanic Snail (Janthina fragilis), which is 

 found too rarely on our shores to be named among 

 their common productions, though it is abundant 

 in warmer latitudes. Its shell is of a beautiful 

 violet colour, and the little animal within is 

 remarkable for the beautiful apparatus by which 

 it floats gracefully along in the waters. This con- 

 sists of an assemblage of air-cells, and resembles 

 a frothy mass. This singular float has no organic 

 connexion with the little mollusk. "It is pro- 

 bable," remarks Captain Cook of this animal, " that 

 it never goes down to the bottom, nor willingly 

 approaches any shore, for its shell is exceedingly 

 brittle, and that of few fresh-water snails so thin ; 

 every shell contains about a tea-spoonful of liquor, 

 which is most easily discharged upon being touched, 



