entomostraca

pl. [Mod. Lat. insects in shells. The name was first given by Otto Frederick Müller, in 1785, in his Entomostraca seu insect a testacea quæ in aquis Daniæ et Norvegicæ reperit. [Entomostraca or Shelled Insects which inhabit the Danish and Norwegian waters.] Fr. entomostracés (Latreille). From Gr. entomon = an insect, and ostrakon a shell.] 1. Zool .: A great sub-cla of Crustaceans. When the name Entomostraca was first given, [Etym.] the Arachnid a (Spiders) and the Crustacea (Crabs) were included in the Insect cla ; now all these are regarded as distinct and equal in rank, though not in numbers. Prof. Thomas Rupert Jones, F. R. S., ., thus defines the Entomostraca: "Animal aquatic, covered with a shell or carapace of a horny consistency, formed of one or more pieces, in some genera resembling a cuira or buckler, and in others a bivalve shell, which completely, or in great part, envelops the body and limbs of the animal. In other genera the animal is invested with a multi valve carapace, like jointed plate armor; the branchise are attached either to the feet or to the organs of mastication; the limbs are jointed and more or le setiferous. The animals, for the most part, undergo a regular moulting or change of shell as they grow; in some cases this amounts to a species of transformation." They may be seen in numbers in ponds, pools, even in water-pipes, and move by a jerking motion. They are thus cla ified: Legion or Division I.-Lophyropoda. Order 1. Ostracod a; 2. Copepod a. Legion or Division II.-Branchiopod a. Order 1. Cladocera; 2. Phyllopod a; 3. Trilobita (?); 4. Merostomata(?). 2. Palæont .: The Copepod a and Cladocera have not yet been found fo il, the other orders have. The Cypride (typical genus Cypris) found so abundantly in the Carboniferous and other rocks, and still existing, are of the order Ostracod a [CYPRIDE, CYPRIS.] Its a ociate, Cythere (q. v.), has also ranged from Palæozoic times till now. Most of the Phyllopod a, except Estheria (q. v.), are Paleozoic. The Trilobita very characteristic, though not exclusively, Silurian fo ar They extend from the Cam brian to the Lower Carboniferous rocks. The Merostomata range from the Upper Silurian till now. ěn-to-mos-tra-can, a. & s. [ENTOMOSTRACA.] A. As adj.: Pertaining or relating to the Entomostraca. B. As subst. A small Crustacean belonging to that sub-cla . ěn-to-mos-tra-cous, a . [Mod. Lat. entomos trac (a) (q.v.); Eng., ., suff.- ous .] Pertaining or relating to the Entomostraca. en-to-mot-o-mist, s. [Eng. entomotom(y); -ist.] One who anatomizes insects; one who practices entomotomy.