The abundance of these animals varies from year to year; adults have been captured at all times of the year, but are not found near the surface during stormy weather.

Usually in March and early May, but some animals in the breeding condition can be taken as late as July.

A. Care of Adults: No information is available.

B. Obtaining Embryos: Mature animals can be recognized by the white or cream-colored gonads lining the gastric pockets. Eggs and developing larvae are found in the brood-pouches along the oral lobes; they appear as greyish specks to the unaided eye, and can be dissected out into a drop of sea water on a slide, for examination. The early cleavage stages and blastulae are found in the region of the mouth.

C. Methods of Observation: If active planulae are placed in clean Syracuse dishes of sea water, they will attach and metamorphose. 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.

NORMAL DEVELOPMENT

A. Early Stages of Development: Maturation probably occurs in the gonad. The mature eggs, each with the second polar body clinging to the delicate egg membrane, then dehisce into the gastric pouches where fertilization occurs; the eggs lodge in folds of the oral lips, where they continue to develop until the planula stage. Cleavage is total, and may or may not be equal; often it is slightly irregular. 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 spherical gastrula soon becomes oval and elongates into an active planula (1910) for details of early development; Okada (1927) describes the details of gastrulation.

B. Later Development: The free-swimming planulae are orange-red in color, well ciliated and opaque. 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. The larva is now in the scyphula or scyphistoma stage. The number of tentacles increases from two to twenty-four. Agassiz (1862) gives diagrams of the planulae and young scyphulae. Apparently, stolonization and colony formation occasionally occur; strobilization is inconspicuous, and often only one strobilus is given off at a time, although occasionally three to five are released. Ephyrae can be produced 20 days after attachment, but normally this process takes 30 to 40 days.

AGASSIZ, L., 1862. Contributions to the Natural History of the United States of America. Vols. 3 and 4. Little, Brown and Co., Boston.

HARGITT, C. W., AND G. T. HARGITT, 1910. Studies in the development of Scyphomedusae. J. Morph., 21: 217-262.

McMurrich J. P., 1891. The development of Cyanea arctica. Amer. Nat. 25: 287-289.

OKADA, Y. K., 1927. Sur l'origine de l'endoderme des discomeduses. Buli. Biol. France et Belg., 61: 250-262.