from the GNU version of the Collaborative International Dictionary of English
- n.pl. One of the subclasses of Crustacea, including a large number of species, many of them minute. The group embraces several orders; as the Phyllopoda, Ostracoda, Copepoda, and Pectostraca. See copepoda, phyllopoda, and cladocera.
from The Century Dictionary and Cyclopedia
- In zoology: Latreille's name for all crustaceans, except the stalk-eyed and sessile-eyed groups.
- In various Systems, one of two main divisions of Crustacea proper (the other being Malacostraca).
- As restricted, defined, and retained by Huxley, those Crustacea which have not more than three maxilliform gnathites and completely specialized jaws, the abdominal segments (counting as such those which lie behind the genital aperture) devoid of appendages, if there be any abdomen, and the embryo almost always leaving the egg as a nauplius-form.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. in some older classifications includes the Branchiopoda and Copepoda and Ostracoda and Cirripedia; no longer in technical use
Sorry, no etymologies found.
But this is perhaps because the minute, almost invisible creatures, or entomostraca, of which the rivers and ponds are full, and which are the main food of the smaller water carnivora, live mainly on decaying vegetable substance, which is practically converted and condensed into microscopical animals before these become in turn the food of others.
But the bottom becomes covered with the suspended matter deposited from the unfiltered water, and probably a considerable number of the minute _entomostraca_ beloved of all fish breed in this.
The water-weeds, both when living and decaying, are eaten by the entomostraca, the entomostraca are eaten by the larvae of insects, the perfect insects are eaten by the fish, and the fish are eaten by men, otters, and birds.
If so, the embryos of the existing vertebrata will shadow forth the full-grown structure of some of those forms of this great class which existed at the earlier periods of the earth's history : and accordingly, animals with a fish-like structure ought to have preceded birds and mammals; and of fish, that higher organized division with the vertebræ extending into one division of the tail ought to have preceded the equal-tailed, because the embryos of the latter have an unequal tail; and of Crustacea, entomostraca ought to have preceded the ordinary crabs and barnacles -- polypes ought to have preceded jelly-fish, and infusorial animalcules to have existed before both.