GLOSSARY. 133 
Undated, waved. formed when the valves are united 
Undulated, with little waves. on the posterior and anterior 
Nopeiates shaped like a horse’s| slopes, 
hoof. 
Unilocular, with a single chamber or Ww 
compartment. 
Univalve, a shell consisting of one | Whorl, a term used by some concho- 
piece. logists for volution, or one of the 
Upper valve, if one valve is attached | wreaths or turnings of the spire 
to other bodies, the free one is the of univalves. 
upper valve. 
Volutions, the wreaths, or spiral Z 
turnings of the shells of univalves. 
Urcelate, swelling in the middle like | Zigzag, having contrary turnings 
a pitcher. and windings. 
Vulva, a spatuliform mark or de« | Zoned, surrounded with one or more 
pression in several bivalve shells ; girdles or bands. 
