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Updated: June 8, 2025
The Crinoid forms include the thought of the modern Star-Fishes and Sea-Urchins; the simple chambered shells of the Silurian anticipate the more complicated structure of the later ones; the Trilobites give the most comprehensive expression of the Articulate type; while the early Fishes not only prophesy the Reptiles which are to come, but also hint at Birds and even at Mammalia by their embryonic development and their mode of reproduction.
ECHINODERMS. This subkingdom comprises at present such familiar forms as the crinoid, the starfish, and the sea urchin. The structure of echinoderms is radiate. Their integument is hardened with plates or particles of carbonate of lime.
But then, on careful consideration of the facts, the objection arises that the stalk, calyx, and arms of the palæozoic Crinoid are exceedingly different from the corresponding organs of a larval Comatula; and it might with perfect justice be argued that Actinocrinus and Eucalyptocrinus, for example, depart to the full as widely, in one direction, from the stalked embryo of Comatula, as Comatula itself does in the other.
It was for a long time supposed that these wonderful creatures were extinct, but dredges have brought up from the dark depths of the sea actual living stone lilies, or crinoids, this being their real name. Few of us will probably ever have an opportunity of studying a crinoid alive, although in our museums we may see them preserved in glass jars.
But then, on careful consideration of the facts, the objection arises that the stalk, calyx, and arms of the palaeozoic Crinoid are exceedingly different from the corresponding organs of a larval Comatula; and it might with perfect justice be argued that Actinocrinus and Eucalyptocrinus, for example, depart to the full as widely, in one direction, from the stalked embryo of Comatula, as Comatula itself does in the other.
We had the crinoid alive for ten or twelve hours. When contracted, the pinnules are pressed against the arms, and the arms themselves shut against one another, so that the whole looks like a swash made up of a few long, coarse twines.
This Crinoid, with its innumerable tentacular arms, appears to have been frequently attached to the driftwood of the liassic sea, in the same manner as Barnacles float about on wood at the present day. There is another species of Extracrinus and several of Pentacrinus in the Lias; and the latter genus is found in nearly all the formations from the Lias to the London Clay inclusive.
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