It is white in color and opaque, and lacks a membrane. The eggs are deposited with an albuminous substance, which provides nourishment for the developing embryos, in a yellow, urn-shaped capsule. This has a short stem and an expanded base, and is laterally compressed. The latter feature distinguishes it from the somewhat similar capsule of Thais. Cleavage is unequal and spiral, with large polar lobes appearing during the first two divisions.
Gastrulation is by epiboly.
The veliger is formed at an early stage. The intestine and anus are late in appearing. The velum is lost before hatching, and the young animal emerges as a well-formed snail. Preliminary observations upon the development of the marine prosobranchiate gasteropods. The breeding of animals at Woods Holl during the month of May, 1898.