So named from its resemblance to an acorn. Shell conical; the coronary
part formed of six very distinct valves, one dorsal, one ventral, and
two pairs of laterals, with or without a calcareous support; operculum
of four articulated pieces, forming a sort of pyramid in the superior
aperture of the tube.
Balanus angulosus.
B. sulcatus.
B. tintinnabulum.
B. nigrescens.
B. cylindraceus.
B. calycularis.
B. roseus.
B. palmatus.
B. stalactiferus.
B. plicatus.
B. duploconus.
B. patellaris.
B. semiplicatus.
B. galeatus.
B. ovularis.
B. miser.
B. amphimorphus.
B. perforatus.
B. lævis.
B. spinosus.
B. radiatus.
B. subimbricatus.
B. rugosus.
B. placianus.
B. crispatus.
B. punctatus.
B. fistulosus.
B. latus.
_B. sulcatus._ The furrowed Balanus.
White; valves nearly smooth; operculum strongly ridged transversely,
with longitudinal, nearly obsolete striæ.
_B. tintinnabulum._ The little Bell Balanus. Pl. 4, fig. 1.
Shell conical; valves strongly and irregularly ribbed; interstices
delicately striated transversely; colour purple.
_B. spinosus._ The spiny Balanus.
Either has no support or a membranous one; armed with spines exteriorly.