Has the form of a cylindrical tube, slightly curved, and open at both ends; one extremity closed by four trapezoidal valves attached to the inner margin, the other end closed by a membrane. The annular ribs which separate the compartments show its progressive growth. Found buried so deeply in the fat of marine animals, particularly whales, that only the operculum and the upper part of the tube are visible. Shell rather elevated, sub-cylindrical, the partitions rather small and indented; the spaces or compartments almost quadrilateral; the inferior much more narrow than the others; the apertures equal and circular; the membrane which closes the superior forming a tube between the four almost equal valves of the operculum.
T. balænarum. The Whale Tubicinella.
Tubular, with transverse ribs, and a ring-shaped margin; operculum bottle-shaped.
2. Coronula. Three species.
Found imbedded in the skin of whales and other marine animals, though not generally at so great a depth as the Tubicinella. Shell in form a little variable and without trace of support; the coronary part formed of six pieces, as in those properly called Balanus, but more regularly disposed in a manner to imitate a kind of crown or tube; spaces alternately hollowed and saliant; operculum not articulated, composed of two pairs of small, level, delicate valves, joined at the aperture of the tube by a considerable membranous part, leaving a passage for the cirrhous appendages of the animal.
Coronula testudinaria.
C. balænarum.
C. diadema.
C. quinquevalvis.
C. testudinaria. The Tortoise Coronula.