Cavolinia gibbosa (d'Orbigny, 1836) forma gibbosa (d'Orbigny, 1836)
Shell globular, transparent, relatively wide (about 68% of length); ventral vault strongly protruding (width about 71% of length). Regularly convex ventral vault does not show forma flava-like edge with sharp top. Anterior part of ventral side perpendicular to shell axis, and may even be slightly elevated. Lateral spines small, caudal spine and upper shell lip pronounced. Juvenile shell starts development as blunt oval protoconch I with fine transverse striations. Only an irregularity in growth separates protoconch I and II. Shell length: 8 mm, width: 5.5 mm.