GLOSSARY OF CONCHOLOGTCAL TERMS. 



Anterior. In bivalves is the side on which the head, or 



part analagous to the head of the animal lies. 

 Aperture or Mouth. The entrance to the spiral cavity of 



univalve shells. 

 Apex. The top or nucleus of the shell, from which point 



the shell, enlarging as it descends, takes a spiral, 



arched, straight, oblique, or irregular course. 

 Axis. The imaginary line, round which the whorls of a 



spiral shell revolve. 



Bivalve. A shell composed of two separate pieces. 

 Body Whorl. The last whorl, constituting the bulk of the 



shell. 

 Byssus. The fibres by which some bivalve shells adhere to 



stones, &c., under the water. 

 Cardinal Teeth. The teeth upon the hinge directly beneath 



the umbones of a bivalve shell, as distinguished from the 



lateral teeth, which are placed at a distance on each 



side. 



Garinated. Applied to any shell having a raised, thin edge. 

 Cinereous. Ash-coloured. 

 Clausium. A ligamentous membrane attached to the animal 



of Clausilia. (See genus Clausilia, p. 52.) 

 Clavate. When one extremity of the shell is attenuated, 



and the other becomes suddenly rounded. 

 Columella. A solid column found by the inner sides of the 



volutions of spiral univalves. 

 Columella lip. The inner lip. 

 Concentric. A term applied to the direction taken by the 



lines of growth in spiral and other shells, (longitudinal 



of some authors). 

 Corneous. Horny. 

 Corroded. When the umbones, apices, and other parts of 



shells are worn away by water. 



