THE NATURAL HISTORY SURVEY. 383 



Ciliary. By means of cilia. 



Ciliated. Having cilia. 



Cilium (plural cilia). A lash; used to designate the hairs on the man- 

 tle, gills, etc. 



Cirrated. Having movable hairs, as the siphons 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 

 (pi. ix, fig. 2). 



Concave. Excavated, hollowed out. 



Concentric. From the same center, as the lines of growth on Sphae- 

 rium, which are parallel with the umbo. 



Confluent. To run together, or into something else, as the muscle scars 

 of some Unios (pi. 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 a nerve 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 (pi. 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 (pi. 

 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 (pi. 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 (pi. xxxii, 

 fig. 15). 



Dentate. With points or nodules resembling teeth, as the aperture of 

 some snails (pi. xxx, fig. 7). 



Denticulate. Finely dentate. 



Depressed. Flattened, as the spire in some snails (pi. xxviii, fig. 4). 



Dextral. Right-handed (pi. 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. 



Dioecious. Having the sexes in two individuals, one male and one 

 female. 



