United States or Vietnam ? Vote for the TOP Country of the Week !
What does it mean, then, when we find the Pentacrinus and Rhizocrinus of the West Indies in deep water only? It seems to me that there is but one explanation of the fact, namely, that in the progress of the earth's growth, we must look for such a displacement of the conditions favorable to the maintenance of certain lower types, as may recall most fully the adaptations of former ages.
Look at the Crinoids, or stalked star-fishes, the "Lilies of living stone," which swarmed in the ancient seas, in vast variety, and in such numbers that whole beds of limestone are composed of their disjointed fragments; but which have vanished out of our modern seas, we know not why, till, a few years since, almost the only known living species was the exquisite and rare Pentacrinus asteria, from deep water off the Windward Isles of the West Indies.
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.
It is represented in the present seas by the delicate and rare Pentacrinus caput-medusae of the Antilles, which, with Comatula, is one of the few surviving members of the ancient family of the Crinoids, represented by so many extinct genera in the older formations. Scales of Lepidotus gigas. Agass. a. Aechmodus Leachii and Dapedius monilifer. a. Aechmodus. Restored outline. b.
Word Of The Day