152 Beautiful Shells. 



amber, and putris means filthy ; but there is nothing 

 repulsive about the shell, which, with its variety, 

 $. gracilis (slender, is found always near water, 



60. 61-62. 63. 64 



60. Achatina acicula (the Needle Agate Shell), Muller. 

 61-62. Succinea putris (the Common Amber Snail), 

 Linnceus. 63. Physa fontinalis (the Stream Bubble 

 Shell), ibid. 64. P. hypnorum (the Slender Bubble Shell), 

 ibid. 



either crawling on mud or damp, or attached to 

 succulent plants. They are never found, however, 

 in the water. Not so Physa fontinalis, as its name 

 implies, physa ((pvaaco), inflated or blown out, and 

 fontinalis, residing in springs or fountains. Yet 

 the creature is herbivorous, feeding on the leaves, 

 especially of Potamogeton, in lakes and rivers. 

 Beneath the water it glides along with moderate, 

 uniform motion, produced by the undulations of its 

 foot. In the air it advances by jerks, without pro- 

 truding its tentacula : and Montagu asserts that it 

 will sometimes let itself down gradually by a thread 

 affixed to the surface of the water, as the IAmax 

 drops itself from the branch of a tree. P. hypnorum 

 is found in ditches and stagnant pools in many parts 



