Gap, an opening in bivalves when the valves are shut as in the
_Pholades_, _Myæ_, &c.
Geminated, marked with a double elevated striæ connecting the wreaths.
Geniculate, keeled.
Genus, an assemblage of species possessing certain characters in
common, by which they are distinguished from all others.
Genera, the plural of genus.
Gibbous, bulged or bulging.
Glabrous, smooth, having a smooth surface.
Globose, globular.
Granulated, beaded, in small grains or beads.
Groove, a hollow channel.