Considerably less is known about breeding habits of marine invertebrates than about many of their other functions, the topic itself being omitted from the most complete treatise available on comparative animal physiology (Prosser et al., '50). I n many species the approximate breeding season is known, but additional data are desirable to define it more precisely. For this reason studies on reproductive cycles in various invertebrates of Monterey Bay were begun several years ago (Giese, '58). The technique consists essentially of determining the ratio of the volume of the gonad to the weight of the body (Lasker and Giese, '54; Bennett and Giese, '55) for a sample of animals at each monthly low tide. In this paper the annual reproductive cycles determined in this manner are described for 4 species of starfishes. Biochemical data gathered at the same time will be reported in detail elsewhere.
METEODS
The starfishes were obtained from several environments near the Hopkins Marine Station. Specimens of Patiria mimida, the sea bat or cushion star, weighing about 100 to 150 grams, were usually obtained from nearby tidepools. Samples of Pisuster ochruceus, the ochre star, weighing from 'Supported in part by Grant 6-5482 from the National Science Foundation and Grant RG-4578 from U. 5. Public Health to A. C. Giese. These funds were supplemented by funds from the Rockefeller Foundation. We are indebted to Mr. Leonard Greenfield for assisting on collecting trips and in assaying the animals on a number of oooasions.