=Bivalve.= When a shell consists of two parts, closing like a double door. The mollusca so protected are commonly called bivalves, as the Mussel. =Brachyura= (Gr. _brachus_, short; _oura_, tail). The tribe of crustacea with short tails, as the Crabs. =Branchiæ= The gills or respiratory organs which extract the oxygen from air contained in water, as in fishes and other aquatic animals. =Buccal= (L. _bucca_, mouth). Belonging to the mouth. =Byssus= (Gr. _byssos_, fine flax). A term applied to the silken filaments or 'beard' of the Mussel and Pinna. =Carapace.= The upper shell of the Crab, &c. =Calcareous.= Composed more or less of lime. =Carnivorous= (L. _caro_, flesh; _voro_, I devour). The animals which feed on flesh. =Caudal= (L. _cauda_, the tail). Belonging to the tail. =Cephalópoda= (Gr. _kephale_, a head; _pous_, a foot). The class of Molluscous animals in which long prehensile processes, or feet, project from the head, as in the Cuttle-fish. =Ciliogrades= (L. _cilium_, an eyelash; _gradior_, I walk). The order of the _acalephæ_ (as the Beröe) which swims by action of cilia. =Cilia= (L. _cilium_, an eyelash). The microscopic hair-like bodies which cause, by their vibratile action, currents in the contiguous fluid, or a motion of the body to which they are attached. =Cirri= (L. _cirrus_, a curl). The curled filamentary appendages, as at the feet of the Barnacles. =Cirripedes=, or =Cirripedia= (L. _cirrus_, a curl; _pes_, a foot). A class of articulate animals having curled, jointed feet; sometimes written Cirrhipedia and Cirrhopoda. =Conchifera= (L. _concha_, a shell; _fero_, I bear). Shell-fish; usually restricted to those with bivalve shells. =Comminuted.= Broken or ground down into small pieces. =Conchology.= The department of science which treats of shells. =Convoluted= (L. _convolutus_). Rolled together. =Cornea= (L. _corneus_, horny). The transparent horny membrane in front of the eye. =Crinoid= (Gr. _krinon_, a lily; _eidos_, a discourse). A family of Star-fishes which bear some resemblance to the form of a lily. The fossils called Stone-lilies, or Encrinites, are examples. =Crustacea= (L. _crusta_, a crust). The class of articulate animals (which includes the Crab, Lobster, &c.) with a hard skin or crust, which they cast periodically. =Decapoda= (Gr. _deca_, ten; _pous_, a foot). The crustaceous and molluscous animals, which have ten feet, such as the Crab, Cray-fish, &c. =Digitate= (L. _digitus_, a finger). When a part supports processes like fingers. =Effete.= Barren, worn out. =Elytra= (Gr. _elytron_, a sheath). The sheath or wing covers of coleopterous insects (Beetles). =Entomostraca= (Gr. _entoma_, insects; _ostracon_, a shell). The order of small crustaceans, many of which are enclosed in an integument like a bivalve shell. =Entomology= (Gr. _entoma_, insects; _logos_, a discourse). The branch of science treating of insects.