This small red starfish is not abundant at Woods Hole, Mass., although some can be obtained by dredging at Lackey's Bay. The sexes are separate and similar in appearance.

The species is said to breed in the early spring (Clark, 1902). Mead (1898) noted that eggs were frequently laid in aquaria at Woods Hole during the third week in April. Larvae were obtained in tows during the month of May (Bumpus, 1898), and motile sperm are found as late as June.

At St. Andrews, Scotland, the breeding period extends from the beginning of February to the end of April (Masterman, 1902).

A. Care of Adults: Adults may be kept in aquaria or large fingerbowls, supplied with running sea water.

B. Procuring Gametes: It is not known whether artificial fertilization is successful in this species. Gametes can be obtained as follows: Cut off an arm along with a pie-shaped piece of the adjacent disc and, with forceps, remove the gonads (pale peach testis or orange-brown ovaries) from the base of the arm. Place them in a small dish of sea water, and allow the gametes to ooze out.

C. Preparation of Cultures: In normal development, the fertilized eggs are protected beneath the body of the female (Coe, 1912), where a brood-chamber is formed, roofed by the raised disc and enclosed by the bases of the arms. The embryos usually remain therein throughout their larval life, and during this period the female does not feed. However, if she is disturbed she will desert the brood permanently, and within a short time resume feeding. Meanwhile, the embryos develop quite normally.

Eggs and assorted larvae can be washed out of the brood-chamber with a pipette. They may be kept in fingerbowls, to which the more advanced larvae will attach. The sea water should be changed frequently, but no special feeding is necessary since there is an adequate supply of yolk.

A. The Unfertilized Ovum: The mature eggs are deep orange in color, and are opaque, due to the presence of a large amount of colored yolk. They are large and spherical in shape, and show some variation in size (800-1200 microns); the majority measure 1000 microns in diameter (Mead, 1898; Masterman, 1902).

B. Fertilization and Cleavage: Fertilization in this species has not been described. There is no definite pattern of segmentation, although the type most frequently observed is holoblastic and unequal. In all cases the egg is transformed gradually into a solid morula, and then, by outward migration of cells, into a blastula with a large blastocoele. The forming blastula may be recognized by a number of transitory indented furrows which form on the surface. Gastrulation is by invagination. See the paper of Masterman (1902) for further details and illustrations.

C. Rate of Development: This is apparently rather slow. The two-cell stage is reached in 6 hours (Mead, 1898); the larvae hatch in 8 to 10 days, and 6 to 10 days later begin their somewhat slow transformation into the adult form (Masterman, 1902).

D. Later Stages of Development: The hatching larvae are demersal, uniformly ciliated, and nearly spherical in shape. They rapidly elongate to a somewhat barrel-shaped form, and develop a dorsal, tripod-like process. The larval stages have neither arms nor mouth. The orange-colored larvae swim about rather slowly for a few days, and then attach by means of the pre-oral process. The larval body, with the exception of this process (which is reduced), is gradually molded into the pentagonal form of the adult. Illustrations of the larval stages may be found in a paper by Masterman (1902).

BUMPUS, H. C., 1898. The breeding of animals at Woods Holl during the month of May, 1898. Science, 8: 58-61.

CLARK, H. L., 1902. The echinoderms of the Woods Hole region. Bull. U. S. Burl Fish., 22: 545-574.

COE, W. R., 1912. Echinoderms of Connecticut. Conn. State Geol. and Nat. Hist. Surv., 19: 1-147.

MASTERMAN, A. T., 1902. The early development of Cribrella oculata (Forbes), with remarks on echinoderm development. Trans. Roy. Soc., Edinburgh, 40: 373-418.

MEAD, A. D., 1898. The breeding of animals at Woods Holl during the month of April, 1898. Science, 7: 702-704.