THE STAR-FISHES. 159 
In concluding this chapter we must not omit to mention the 
Medusas head, one of the most extraordinary productions of 
THE MAGNIFIED LARVA OF THE ECHINODERM. 
(Pluteus paradoxus.) 
marine life. They belong to the Crinoidea, a class of zoophytes 
which swarmed in the Paleozoic seas. Many of the limestones 
PENTACRINUS EUROPEUS. 
are ail but masses of these crinoids. Now the great race is all 
but extinct, and our seas only present two species. One is fished 
up from great depths, in the neighbourhood of the Antilles, and 
