THE NATURAL HISTORY SURVEY. 383 
Ciliary. By means of cilia. 
Ciliated. Having cilia. 
Cilium (plural cilia). A lash; used to designate the hairs onthe man- 
tle, gills, etc. 
Cirrated. Having movable hairs, as thesiphons of Unio. 
Clavate. Club-shaped. 
Cloacal. Referring to the upper or dorsal siphon in pelecypods. 
Coarctate. Pressed together, narrowed. 
Compressed. Flattened out, or pressed together, as some bivalves 
(pl. ix, fig. 2). 
Concave. Excavated, hollowed out. 
Concentric. From the same center, as the lines of growth on Sphe- 
rium, which are parallel with the umbo, 
Confluent. To run together, or intosomething else, as the muscle scars 
of some Unios (pl. xix, fig. 1). 
Conic. Shaped like a cone. 
Connective. A part connecting two other parts, as a muscle connect- 
ing two parts of the body, or anerve connecting two ganglia. 
Constricted. Narrowed. 
Contractile. Capable of being contracted or drawn in, as the tentacle 
of a snail. 
Convex. Bulged out, as the whorls of some snails (pl. xxxvi, fig. 1). 
Convoluted. Rolled together. 
Cordate. Heart-shaped. 
Corneous. Horn-like, as the opercula of some mollusks. 
Corrugated. Roughened by wrinkles, as the shells of some Unios (pl. 
ix, fig. 1). 
Costate. Having rib-like ridges. 
Crenulate. Wrinkled on the edges. 
Crescentic. Like a crescent. 
Cylindrical. Like a cylinder. 
Decollated. Cut off,as the apex of some shells (pl. xxxvi, figure next 
to fig. 8). 
Decussated. With spiral and longitudinal lines intersecting, as the 
sculpture of some shells. 
Deflexed. Bent downward, as the last whorl in some snails (pl. xxxii, 
fig. 15). 
Dentate. With points or nodules resembling teeth, as the aperture of 
some snails (pl. xxx, fig. 7). 
Denticulate. Finely dentate. 
Depressed. Flattened, as the spire in some snails (pl. xxviii, fig. 4). 
Dextral. Right-handed (pl. xxxii, fig. 1). 
Digitiform. Finger-like. 
Dilated. Expanded in all directions, as the aperture of a shell. 
Dimorphism. With two forms or conditions. 
Dimyarian. Having two distinct adductor muscle impressions or 
scars, as in Unio. 
Dicecious. Having the sexes in two individuals, one male and one 
female. 
