Any one of numerous species of echinoderms belonging to the class Asterioidea, in which the body is star-shaped and usually has five rays, though the number of rays varies from five to forty or more.
Many echinoderms (viviparous species and some others).
The process is most clearly observed in the ova of the echinoderms (star-fishes, sea-urchins, etc.
Hertwig has shown that the tiny transparent ova of the echinoderms are the most convenient for following the details of this important process of impregnation.
Especially has the minute examination of the thickness of the test in echinoderms revealed to me unexpected relations between the sea-urchin and the medusa.
If there is a type of Echinoderms characteristic of a geological period, it is the genus Micraster of the cretaceous formation, in its original circumscription.
Our dragnets brought up many specimens of polyps and echinoderms plus some unusual shells from the branch Mollusca.
A Silurian Scorpion] To the echinodermsthere is now added the blastoid (bud-shaped).
All Echinoderms have locomotive organs peculiar to themselves, a kind of suckers which may be more or less numerous, larger or smaller, in different species, but are always appendages of the same character.
The development of Echinoderms forms one of the most wonderful chapters in the annals of Natural History.
In Echinoderms as a class, the body presents three regions differing in structure, and on the greater or less development of these regions or systems, as we may call them, their chief differences are based.
All Echinoderms without exception have ambulacral tubes, even though in some there are no external ambulacral suckers connected with them.
And yet the fundamental structure of the class of Echinoderms is represented as distinctly by any one of its five orders as by any other, and is absolutely identical in all.
He also suggests that the development of the later larval forms of the Echinoderms is the same in kind.
The comparison of the Acalephs with the Echinoderms is still easier, for they both have tubes; but in the latter the tubes are inclosed in walls of their own, instead of traversing the mass of the body, as in Acalephs, etc.
The tracing of this history, and the explanation of the general characters of Echinoderms and of the differentiating features of the classes in accordance therewith, constitutes the Pelmatozoic theory.
The theory which had most influence on the conceptions of Echinoderms in the two concluding decades of the 19th century was that of Loven, elaborated by P.
The Pelmatozoic theory thus regards the Pelmatozoa as the more ancestral forms, and the Pelmatozoan stage as one that must have been passed through by all Echinoderms during their evolution from the Dipleurula.
Bell, Catalogue of the British Echinoderms in the British Museum (London, 1892); P.
Instead of discussing all these questions separately, with the details necessary for an adequate presentation of the argument, we shall now sketch the history of the Echinoderms in accordance with the Pelmatozoic theory.
The whole social and political fabric of the British Empire depends upon the efficiency of its industrial system.
The eulogies showered upon it in the past were no longer considered adequate.
Newman, History of the Arians of the 4th Century).
At Claiborne, in Alabama, no less than 400 species of marine shells, with many echinoderms and teeth of fish, characterise one member of this system.
Besides these, however, the same ancient schists have yielded two genera of brachiopods, Orthis and Orbicula, a Pteropod of the genus Theca, and four echinoderms of the cystidean family.
Other Echinodermsare rare, a few Sea-Urchins only being known: these have a complex structure, with many more plates on their surface than are seen in the modern genera of the same group.
I have been working in all things with a reference to wide views of zoological philosophy, and the report upon the Echinoderms is intended in common with the mem.
He also showed the distinctness of echinoderms from polyps, thus anticipating Leuckart, who established the phylum of Coelenterata nearly half a century later.
The metamorphosis of the Echinoderms included under this head in Thompson's article is now known not to be a proper case of alternations of generations.
It appears to be very rare in Echinoderms (Echinaster Sarsii).
The dredge was also put over, and hauled in with unimportant results, only a few echinoderms being obtained.
These echinoderms are very rare, few specimens having been met with, until the deep-sea dredgings of the "Challenger" brought them more into notice.
In this torpor the echinodermsand even the molluscs live to-day.
I think I have said enough of these different classes to show that Polyps as a whole are inferior to Acalephs as a whole, and that Acalephs as a whole are inferior to Echinoderms as a whole.
There was a rich development of echinoderms (sea urchins and star fishes), but nothing is perfect, owing to the hardness of the rock (Dr.
We will conclude our short account of the British echinoderms with a description of the peculiar Sea Cucumbers, which belong to the division Holothuroidea.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "echinoderms" in a variety of sentences. We hope that you will now be able to make sentences using this word.
