264 
THE OCEAN WORLD. 
Star-fishes are exclusively and essentially beings of the sea ; they 
are never seen in fresh water ; they dwell amongst the submarine 
herbage, seeking for sandy coasts ; they generally are found at moderate 
depths, but there are some species which are found at the great depth 
of a hundred and fifty fathoms. 
Asterias are met with in almost every sea and under all latitudes, 
but they are most numerous and their forms are more richly varied 
in the seas of tropical regions. There are about a hundred and forty 
species described. 
The body of the Asteria is supported by a calcareous envelope com- 
posed of j uxta-posed pieces at once various and numerous. The 
number of these pieces is estimated at more than eleven thousand m 
the Eed Sea Starfish ( Asterias ruhens, Tig. 105), a species very 
Fig. 106. Asterias aurantiaca (Lamarck). 
common in Europe. The body of the Asterias rubens is likewise 
furnished with spines, granules, and tubercules, the shape, number, 
