104 GLOSSARY. 
conotdea, cone-like. , 
contécta, covered. 
contortus, twisted together. 
contractile, able to become shorter. 
convex, bulging out. 
corneus, horny. 
corvus, a crow, applied to a very dark var. of L. palustris. 
costata, ribbed. 
cristata, crested. 
orystallinus, crystalline. 
curta, short. 
curvirdstris, with curved beaks. 
Cyclostoma, round mouth; name of a genus. 
Cyclostomatide. Name of a Family of mollusks, from the 
typical genus Cyclostoma. 
cygnea, belonging to swans. 
Dp. 
deciduous, liable to fall off. 
decollata, shortened from the top, truncated. 
dectiissated, intersected by cross-lines. 
dénticle, a small tooth. 
dentition, see lingual. 
depréssa, flattened. 
depressitiscula, somewhat flattened. 
déxtral. A univalve is said to be dextral when the mouth 
opens to the observer’s right as he holds it with the 
spire pointing upwards. 
deatrorsa, turned to the right hand. 
dilatdtus, expanded. 
Dillwynii, named after Dillwyn. 
disciformis, formed like a circular plate. 
