GLOSSARY. 167 
contortus, twisted together. 
contréctile, able to become shorter. 
convex, bulging out. 
corneus, \ ‘ 
-horny. 
cornea, J 
corvus, a crow; applied toa very dark variety of Z. palustris. 
costéta, ribbed. 
ae \ crested. 
cristéta, J 
crystdllina, crystalline. 
curta, short. 
curvirostris, with curved beaks. 
Cyclostoma, round mouth. 
cygnea, pertaining to swans. 
cylindrécea, cylindrical. 
deciduous, liable to fall off. 
decollétum, truncated. 
dectissated, intersected by cross lines. 
dénticle, a small tooth. 
dentition arrangement of teeth. 
depiléta, denuded of hairs. 
depréssa, flattened. 
depressiuiscula, somewhat flattened. 
déxtral. A univalve is said to be dextral when the mouth 
is on the observer’s right’ as he holds it facing him, 
with the spire upwards. 
