An irregular tube, with branches or projecting tubes at the closed end;
within it is one free or moveable valve, united by a ligament to
another, which is blended with the tube; this distinguishes it from the
Aspergillum. Found in sand and coral.
Shell oval, very slightly elongated, striated longitudinally, slightly
irregular; equivalve, inequilateral; hinge a little variable; ligament
exterior; two well-marked distant muscular impressions; a calcareous
sub-cylindrical tube, more or less completely surrounding the shell, and
terminated before by a single orifice.
_C. aperta._ The open Clavagella.
Tube erect, adhering; aperture waved, entire, expanding, funnel-shaped,
leaving the two valves open or uncovered in all their anterior part;
with an ovate face valve.