"Sulci are furrows.
"Fornicated signifies arched, greatly excavated.
"Umbo is the swelling part near the beak of bivalve shells; the same as boss.
"Longitudinal, running nearly the whole length of the shell in univalves.
"Concentric, having the same centre.
"Convolute, when the exterior whorls spirally involve the interior.
"Varices, longitudinal, gibbous sutures formed in the shell, at certain distances on the whorls.
"Carinated, having the form of the keel of a boat."