Caecum sp. A

Figures 123 A–E, 128G

Material examined. NHMLAC: LACM 1972 - 52.67, Herradura Bay, Costa Rica, 3–16 m, 2 sh .

Diagnosis. Teleoconch subcylindrical, with slight increase in diameter from posterior end to aperture. Surface semi-translucent to opaque white, smooth with fine axial growth lines. Septum mucronate, with low rounded mucro. Apertural end with abrupt swelling crossed by axial rings. Periostracum thin, yellow.

Distribution and Habitat. Currently only represented by two specimens from Costa Rica.

Remarks. Caecum sp. A is somewhat similar to the Indo-Pacific species Caecum gulosum Hedley, 1899 . However, C. gulosum has a proportionally larger diameter with more pronounced axial sculpture (Fig. 123F).