ECHINODERMATA. . 255° 
are found at moderate depths, but there are some species which are 
found at the great depth. of 1,250 fathoms. 
Star-fishes 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. 
Fig. 104.—Asterias rubens (Lamarck). 
The bddy ot the Asterias is supported by a calcareous envelope 
composed’ of juxta-imposed’ pieces at once various and numerous. 
The number of these pieces is estimated at more than 11,000 
in the’ Red Sea Star:fish “(Asterias rubens, Fig.’ 104), a species 
very common in Europe. The body of the’ Asterias rubens is 
likewise “furnished with’spines, granules, and tubercles, the shape, 
number, and disposition of which serve in many.cases to characterise 
the genera and the species. 
