EXPLANATION OF TERMS. 227 



Turbinate: The body swelling, and spire com- 

 paratively small; from the Latin turbin 

 is y 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 us, 



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. 



Farices. Longitudinal gibbous sutures formed 

 Q 2 



