106 GLOSSARY. 
Carnivorous. Flesh-eating. 
Cartilage, of the hinge. An elastic body inside of the liga- 
ment of bivalve shells, which is compressed, when the shell 
is closed by the contraction of the adductor muscle, and 
reopens the shell when the muscle is relaxed. 
Cephalic. Of, or relating to the head. 
Cicatrix. A scar. The impressions on the inside of bivalves, 
caused by the insertion of the adductor muscles. These 
are single in the oyster, two in the mussel. 
Columella. The central axis round which spiral shells are 
coiled. 
Conchology. ‘The study of shells, and their inhabitants. 
Cordiform. Heart-shaped. 
Crenulated. Notched, with rounded teeth. 
Dentate. ‘Toothed. 
Depressed. With a low, flattened, spire. 
Dextral. Shells whose aperture is on the right of the columella. 
Discoid. Flat, the whorls of the spire being on the same 
level. Ex., Planorbis, etc. 
Emarginate. Notched; appearing as if cut off. 
Epidermis. The cuticle, or membrane, which envelops some 
species of shells. It varies greatly in texture and appearance. 
Equilateral. Having the right and left sides of the valves 
equal. 
Equivalve. With the two valves equal. 
Gasteropod. Belly-footed. A mollusk with a ventral disk, or 
foot for walking. Ex., the slugs. 
Genus. Kindred. Applied to several things with a common 
character. Ex., the snails. 
Globose. Spherical. 
Helix. A coil, or spiral. Hence the genus Helix. 
Hermaphrodite. Applied to those mollusks which recipro- 
cally perform the functions of both sexes. 
Hiatus. A gape, or opening found in some bivalves when 
the shell is closed. 
Hinge. The thickened, and mostly toothed, margins of the 
valves of a bivalve shell, where they are joined together. 
The hinge-teeth are variously named —those under the 
