1G8 THE ELEMENTS, &C. 



Unilocular, with a single cavity. 



Univalve, shells of one valve, or com- 

 plete in one piece. 



Volutions, the wreaths, or turnings of 

 the shells of univalves. 



Urceolate, swelling in the middle like 

 a pitcher. 



Vulva, a spatulated mark in the Venus 

 tribe ; formed when the valves are 

 united on the posterior and anterior 

 slopes. 



W. 



Whorl, one of the wreaths or turning 

 of the spire of univalves. 

 Z. 



Zigzag, having contrary turnings and 

 windings. 



Zoned, surrounded with one or more 

 girdles. 



J. Gleavc, Printer, Manchester. 



