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T W O FIQURES
A recent abstract by Gould ('47) again raises the question as to whether the young, sexually immature snail of this species must have association with mother individual of larger size in order to become sexually mature in the male phase. It was assumed that the question had been satisfactorily answered in the negative by the observations and experiments reported by Coe ( '35, '36, '38, '38a) but additional mid presumably more conclusive evidence is available and will be presented in this paper. This evidence is based on experimerits which differed from those so comprehensively reported by Gould ( '17, '17a, '19) and which yielded different results. I t should be recalled that the species of Crepidula and those of the other genera of the Capulidae are typically protandric, most individuals experiencing a functional male phase when young and later changing by a transition stage to the female phase (fig. ). The latter continues f o r the remainder of the animal's lifetime. The male phase is characterized by the outgrowth of a long copulatory organ, phallus, behind the right tentacle. This phallus begins its growth with the onset of active spermatogenesis and is absorbed when spermatogenesis ceases before the beginning of the transition stage.
Contributions from the Scripps Institution of Oceanography, New Series, no. 368.