Fossil crinoids have long been known, and beautiful specimens may be seen in all our museums, but the fact that they still live upon the globe is a modern discovery.
The history of the development of crinoidsis very interesting.
The crinoids resemble lilies so closely that they are called stone lilies.
Sea urchins have become plentiful; crinoids abound until the Cretaceous, where they begin their decline to their present humble station.
Among the echinoderms, crinoids are now exceedingly abundant, sea urchins are more plentiful, and sea cucumbers are found now for the first time.
Crinoids are rare at the present time, but they grew in the greatest profusion in the warm Ordovician seas and for long ages thereafter.
The "Pentremites" resemble the Crinoidsin having a cup-shaped body (fig.
A genus of Crinoids in which the column is five-sided.
In North America the remains of Crinoids are even more abundant at this horizon than in Britain, and the specimens found seem to be commonly more perfect.
The polished surface intersects the columns of the Crinoids at different angles, and thus gives rise to varying appearances.
Allied to the Crinoids are the singular creatures which are known as Cystideans (fig.
One of the most characteristic Jurassic genera of these "stalked" Crinoids (though not exclusively confined to this period) is Pentacrinus (fig.
The commonest of the Carboniferous Crinoidsbelong to the genera Cyathocrinus, Actinocrinus, Platycrinus, (fig.
The Crinoids were represented by the genera Platycrinus and Cyathocrinus.
As to the Zoophytes, they consist chiefly of Crinoids and Corals.
In some crinoids which have no trace of a stem (e.
Carpenter published important papers on fossil crinoids in the Journal of the Geological Society, on Cystidea in that of the Linnean Society, 1891, and, together with R.
Some crinoids have yet another circlet below these, the constituent plates of which are called "infrabasals," and are situated radially.
That the crinoids are all deducible from some such simple form as that above described under the head "calycinal theory," is now generally admitted.
The Silurian crinoids and cystids of Sweden have been illustrated in N.
Palaeontographica); while the multitude of North American palaeozoic crinoids has been attacked by C.
Angelin's Iconographia crinoideorum (1878); the Palaeozoic crinoids and cystids of Bohemia are dealt with in J.
Carpenter's proof of the nervous nature of the chambered organ and axial cords of crinoids (Proc.
The Ophiurans approach the Crinoids more nearly than any other group of Echinoderms, and in our classifications are placed next above them.
It seems a contradiction to say, that, though these Crinoids were the only representatives of their Class in the early geological ages, while it includes five Orders at the present time, Echinoderms were as numerous and various then as now.
The Troehites were recognized as simply the broken portions of the stem of some of these old fossil Crinoids, and the Crinoids themselves were seen to be the ancient representatives of the present Comatulae and Star-Fishes with stems.
Among the Crinoidsor Stone-lilies of the Lias, the Pentacrinites are conspicuous.
The same phenomena may be observed in joints of Crinoids from the Palæozoic rocks, and they constitute proofs of organic origin even more irrefragable than the filling with serpentine.
The mode of filling thus suggested for the chambers and tubes of Eozoon, is precisely that which takes place in modern Foraminifera filled with glauconite, and in Palæozoic crinoids and corals filled with other hydrous silicates.
At the latter, the first cast of the large dredge was made on a ledge of shoals in a depth of eighty fathoms, and, among countless other things, a number of stemmed crinoids and comatulae were brought up.
The trilobites are gone, and of the crinoids only a remnant is left.
Many creatures, such as the trilobites, die out, and many other forms such as the crinoids or sea lilies become fewer in kind and of less importance.
At the meeting of the American Association, 1849, a paper on the fossil crinoids of Tennessee, by Professor Troost, was read by Professor Agassiz.
The Crinoids culminate in the Mesozoic, and are not known to give origin to anything higher.
In later times the group of Crinoids has been gradually dwindling in number and variety.
The Pentacrinus bears the closer relation to the more ancient Crinoids (Fig.
The order of Crinoids has diminished so much in modern geological times that we must consult its fossil forms in order to understand fully the peculiar adaptation of the Echinoderm plan in this group.
The Crinoids are very scantily represented in the present creation.
Defn: A genus of crinoidsbelonging to the Blastoidea.
Defn: A red and purple pigment found in certain crinoids of the genus Pentacrinus.
The Crinoids are as numerous and beautiful as in any other period, and here for the first time we meet with the new and higher type of the sea-urchin, in large and beautiful species.
In the Crinoids the generative rachis consists of a tube, the epithelium of which is formed of the primary germinal cells.
The development of these peculiar parasites on Crinoids has been investigated by Metschnikoff (No.
In the Crinoids they have the form of a hollow rachis completely surrounded by a blood-vessel.
A red and purple pigment found in certain crinoids of the genus Pentacrinus.
The Trilobites stand in the same relation to the modern Crustacea as the Crinoids do to the modern Echinoderms.
The central calcareous zone abounds in corals andcrinoids as well as in numerous brachiopods.
Crinoids were very abundant in some parts of the Devonian sea, though they were relatively scarce in others; they include the genera Melocrinus, Haplocrinus, Cupressocrinus, Calceocrinus and Eleuthrocrinus.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "crinoids" in a variety of sentences. We hope that you will now be able to make sentences using this word.
