TERMS USED IN DESCRIBING MOLLUSKS 



Abductor muscles : Muscles which move parts away from the 

 axis. 



Adductor muscles : Muscles which draw parts together ; oppo- 

 site of abductor. 



Aperture : Opening of the spiral shell. 



Bilateral symmetry : Having two equal sides, divided by a 

 central axis. 



Branchice: Gills, or breathing-organs; organs subservient to 

 respiration through water. Same as ctenidia. 



Buccal mass : The mouth-parts as a whole ; the organ of pre- 

 hension and mastication of food ; the pharynx : present in all 

 mollusks except lamellibranchs. 



Canal : A narrow prolongation of the aperture of a spiral shell. 



Carinated : Ridged as if keeled ; having a keel. 



Cinereous: Ash-gray; having the color of wood-ashes. 



Cirri, plural of Cirrus: Filamentous appendages. 



Columella : An upright pillar in the center of most of the uni- 

 valve shells, round which the whorls are convoluted. 



Concrescent : Growing together ; uniting. 



Cordate : Heart-shaped. 



Costce, plural of Costa : Ridges of a shell. 



Crenulated: Having a series of notches; marked as with 

 notches, as the indented margin of a shell. 



Crystalline style: A transparent gelatinous substance of un- 

 known function, which fills, at times, the stomach-parts of certain 

 mollusks. 



Ctenidia, plural of Ctenidium: Gills, or breathing-organs, 

 adapted to water-respiration. 



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