On interspecific hybridization in Ostrea.

Science, a weekly journal founded in 1880, is published each Friday by the American Association for the Advancement of Science at the Business Press, 10 McGovern Ave., Lancaster, Pa. Editorial and Advertising Offices, 1515 Massachusetts=Ave., N.W., Washington 5, D. C. Telephone, Executive 6060. Cable address, SCIMAG, Washington, D. C. Entered as second-class matter at the Post Office at Lancaster, Pa., January 13, 1948, under the Act of March 3, 1879. Acceptance for mailing at the special rate postage provided for in the Act of February 28, 1925, embodied in Paragraph (d-2) Section 34.40 P.L. & R. of 1948. Manuscripts submitted for publication should be sent to the Editorial Office, with stamped, self-addressed envelope enclosed for possible return. The AAAS assumes no responsibility for the safety of the manuscripts or for the opinions expressed by contributors. Annual subscription, $7.50; single copies, $.25: foreign postage, outside the Pan-American Union, $1.00; Canadian postage, $.50. Remittances and orders for subscriptions and single copies should be sent to the Circulation Department, Science, 1515 Massachusetts Ave., N.W., Washington 5, D. C. Membership correspondence for the AAAS should be addressed to the Administrative Secretary at the same address. Change of address. Four weeks' notice is required for change of address. This should be sent to Science Recorder' 1515 Massachusetts Ave., N.W., Washington 5, D. C. When ordering a change, it is necessary to furnish an address stencil label from a recent issue. Claims for a missing number will not be allowed if received more than 60 days from date of issue. No claims allowed from subscribers due to failure to notify the Circulation Department of a change of address or because an issue is missing from their files, or for any reason from subscribers in Central Europe, Asia, or the Pacific Islands (other than Hawaii). The AAAS also publishes The Scientific Monthiy. Subscription rates on request. 3