Usually in March and early May, but some animals in the breeding condition can be taken as late as July. No information is available. Mature animals can be recognized by the white or cream-colored gonads lining the gastric pockets. The early cleavage stages and blastulae are found in the region of the mouth. If the watch glasses with the attached scyphistomae are removed to aquaria and the larvae fed echinoderm larvae, copepods, etc., they will live for several months.
Maturation probably occurs in the gonad.
A cleavage cavity appears early and a hollow, single-layered blastula is formed. Gastrulation is by invagination, although at times this may be accompanied by delamination. The anterior end is distinctly broader than the posterior end, and the old blastopore, which develops into the mouth, may be visible. After a free-swimming life of from 20 to 40 days, the larva settles down and attaches by the narrow end to the substrate. There is an elongation of the body, followed by the acquisition of tentacles about the gaping mouth.