EXPLANATION OF TERMS. 227 



Turbinate. The body swelling, and spire com- 

 paratively small ; from the Latin tur- 

 bin is, of a whirlwind. 



Turreted. The whorls gradually decreasing to 

 a fine point ; the length of turreted shells 

 greatly exceeds their breadth. 



Turgid. Swollen, puffed up. 



Teeth. The pointed protuberances at the hinge 

 of bivalve shells; the cardinal or central 

 teeth are those situated on the hinge ; 

 the Lateral teeth are those at the sides 

 of the hinge, and are often remote. 



Tuberculated. Covered with tubercles, or small 

 protuberances. 



Tortuous. Twisted; from the Latin tort MS, 

 twisted. 



Transverse. Placed across, or crossways. 



Truncated. Cut short or abruptly off at the 

 end. 



Umbones, or Bosses. The swelling parts of 

 bivalve shells near the beaks ; from umbo, 

 the boss of a shield. The highest points 

 of these are considered the summits. 



Umbilicus. A small hollow at the base of the 

 columella, visible underneath. 



Undulating. Wave-like ; from undula, a little 

 wave. 



Univalve. A shell composed of one valve ; from 

 unws, one, and valve. 



Volution or Whorls. The distinct turns of 

 the spire. 



Varices. Longitudinal gibbous sutures formed 

 Q 2 



