In infancy the Feather-star is seated at the extremity of a long
slender jointed stalk, attached at its lower end, whence it rises
erect, like a plant. Indeed the whole animal, in this condition, with
its cup-like base and elegantly incurving arms, seated on its tall
stem, has so close a resemblance of outline to a flower, that the
fossil specimens, which are very numerous, and of large size, are
known as Lily-stones, and technically as _Encrinites_, which word has
the same allusion. After a while, the radiating portion, or flower,
separates from the stalk, and swims freely, contracting its arms to
give the impulse, in the manner of a _Medusa_.
Who, on looking at these two creatures side by side,--the Sea-Urchin
and the Encrinite,--would imagine that they possessed any close natural
relationship, or would suspect that they could have been framed on the
same model? Yet it is really so; there is a common plan of structure
in both; pervading, too, many intermediate forms, which at first sight
would seem to manifest as little resemblance to the one as to the
other. It would, in fact, be easy to select from any well-furnished
museum a continuous chain of specimens, whose links approach each
other so closely as to form an unbroken series from the Urchin to the
Feather-star.