Vol. 138, No. 2 April, 1970 THE BIOLOGICAL BULLETIN PUBLISHED BY THE MARINE BIOLOGICAL LABORATORY HYDROID AND YOUNG MEDUSA STAGES OF DIPURENA STRANGULATA (HYDROZOA, CORYNIDAE)1'2 DALE R. CALDER Virginia Institute of Marine Science, Gloucester Point, Virginia 23062 The genus Dipurena was established by McCrady (1857) for two species of Anthomedusae from Charleston Harbor, South Carolina. Mayer (1910a) synonymized McCrady's genus with Slabberia of Forbes (1846), but later (Mayer, 1910b) recognized Dipurena as the valid name of the genus because Slabberia had been applied to a leptomedusan by Oken (1815). Kramp (1961) discussed seven species of Dipurena but considered at least two of them doubtful, D. brownei (Bigelow) and D. dolichogaster Haeckel. The validity of D. pyramis (Haeckel), a somewhat aberrant species of uncertain systematic position, has also been questioned (Kramp, 1959). The remaining four, D. halterata (Forbes), D. strangulata McCrady, D. ophiogaster Haeckel and D. reesi Vannucci, are relatively well-known and recognized species. An additional species, D. siniulans, was briefly described by Bouillon (1965). Of the latter five, both hydroid and medusa phases are known for all but D. strangulata, the type species of the genus and a rather common hydromedusa along the United States east coast. During a recent survey of the Hydrozoa in southern Chesapeake Bay, unidentified capitate hydroids were found on sponges in the York River, Virginia. Through life-history studies the hydroids were linked to the medusa D. strangulata. A description of the hydroid and young medusa is the purpose of this paper. MATERIALS AND METHODS The hydroid Dipurena strangulata was found on colonies of the sponge Microciona prolif era collected from oyster grounds by dredging and from pier 1 Contribution No. 338 from the Virginia Institute of Marine Science, Gloucester Point, Virginia 23062. 2 This paper was written during tenure of a National Research Council of Canada Postdoctoral Fellowship at the Museum of Natural Sciences, National Museums of Canada, Ottawa 4, Ontario. 109 Copyright ©1970, by the Marine Biological Laboratory Library of Congress Card No. A38-518 This One I@ DhIIIIIU@ @I liii I1@ U@ II@ @I III@III Ill III@I 1U8B-TYS-BX4A