180 GLOSSARY. 
trochéides, shaped like the marine shell Z/ochus, i.e., pyra- 
midal. 
trincate, ending abruptly. 
truncatula, slightly truncate. 
tubérculate, furnished with pimples. 
tumidula, somewhat swollen. 
tumidus, swollen. 
type, a standard of comparison. 
typical, resembling the type. 
Ud. 
umbilicus, the navel ; applied to univalve shells, the cavity 
formed by the whorls when they do not form a solid 
axts or columella. 
umbo, the knob or boss in the centre of a shield ; applied 
to bivalves, the wszbones (or beaks) are the protruber- 
ances by the hinge, which constituted the infant shell. 
unidentdta, having one tooth. 
unduléta, marked with wavy lines. 
wnicolor, of one color. 
Unio, a pearl. 
univalve (a shell), consisting of one piece. 
Ne 
Valvdta, having a valve (i.e., oferculum). 
valve, a complete part of a shell. 
variegdta, variegated. 
