Conical, vertex slightly spiral, pointed, and recurved; exterior pale fawn colour, and the outer margin bordered with a fringed epidermis; interior sometimes of a very bright pink or rose colour.
5. Calyptræa. The Cup and Saucer Limpet. Four species.
This genus of shells is remarkable for having in the interior cavity a transverse funnel or tongue-shaped testaceous appendage, from which originated its common name.
Shell conic, base orbicular; summit vertical and imperforated; cavity deep, having at its interior summit a tongue-like appendage. This appendage is sometimes vertical and sometimes like a horseshoe, having on it a muscular impression of variable form.
Calyptræa extinctorium.
C. lævigata.
C. equestris.
C. tectum-sinense.
C. extinctorium. The extinguisher Calyptræa.
Species in which the internal appendage is horn-shaped; colour brownish.