168 CONCHOLOGIST’S COMPANION. 
diously directed to produce important consequences 
in the animal economy, are discoverable in such 
species as either inhabit aquatic plants, or are de- 
cidedly oceanic. 
The H. vivipara, and H. tentaculata, Viviparous 
and Olive Helices, are furnished with small pieces of 
shell, that answer the purpose of doors or shutters, 
by means of which they close their dwellings, and 
completely exclude the water. 
The inhabitant of the H. ianthina, or Violet Helix, 
swims at liberty in the sea. It is furnished with 
four horns, or horn-shaped tentacula, and a membra- 
naceous bag, consisting of small bladders, which it 
inflates at pleasure, and is thus enabled to float on 
the surface of the water. It is also endowed with 
the property of emitting a phosphorescent light, and 
stains the hand of a rich purple colour, which is not 
easily removed. These small bladders mark the 
character of the animal; as a creature floating in 
the ocean, or as one attached to marine substances. 
It is highly interesting to observe these little 
Helices, either inflating their marine balloons, and 
skimming the surface of the billows, or seeking, in 
the hollow of the waves, a shelter from the wind: 
to watch them as they slowly retire into those 
sea-covered regions, dotted with plants of innu- 
merable shades and colours, which, like the animals 
