STUDIES ON THE CYCLOSTOMATOUS BKYOZOA. By Ferdinand Canu, Of Versailles, France, AND Ray S. Bassler, Of Washington, District of Columbia. During our studies of the North American Early Tertiary cyclo-stomatous Bryozoa, published as a part of our monograph of 1920,^ we had occasion to extend our researches to many additional species, both living and fossil, for purposes of comparison and in order to test our classification. Our efforts were particularly directed to specimens bearing ovicells, as it is upon the function of reproduction that our classification is based in part. Species showing no ovicells, however, were also studied, often by means of thin sections, to de-termine the method of gemmation and the occurrence and variation in structure of the several kinds of adventitious and accessory tubes. Our notes upon these additional specimens contain so many new observations upon both described and undescribed species that we thought it advisable to publish them in a series of papers under the above general title. 1. FOSSIL AND RECENT PARALLELATA AND RECTANGULATA. We have found Waters' two subdivisions of the Cyclostomata, the Parallelata, and Rectangulata to be not only convenient but valuable in classification. The present paper deals with both recent and fossil species of the Parallelata and Rectangulata genera listed on the fol-lowing pages. A second paper now in preparation, discusses the Lower Cretaceous Cyclostomatous Bryozoa from the two classic localities, Farringdon, England, and Sainte Croix, Switzerland. The researches herein recorded were made possible through a grant from the American Association for the Advancement of Science, for which assistance we are highly grateful. 1 1920, Canu and Basaler. North American Early Tertiary Bryozoa, Bull. 106 U. S. National Museum (2 vols.), 879 pages, 162 pis. No. 2443— Proceedings U. S. National Museum. Vol. 61, Art. 22. 1
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