DESCRIPTIONS OF NEW WEST AMERICAN MARINE MOLLUSKS AND NOTES ON PREVIOUSLY DESCRIBED FORMS. By Paul Bartsch, Curator, Division of Marine Invertebrates, United States National Museui The present paper describes and figures new species of West American mollusks belonging to groups which I have previously monographed. It represents material that has come to hand since the monographs were issued. By far the larger portion of the specimens vvere discovered by the U. S. Bureau of Fisheries steamer Albat7'oss, but many were contributed by private West American collectors, whose zeal and efforts continue to materially increase our knowledge of marine life from year to year. In addition to the descriptions of new forms, references to species (chiefl}' fossil) de-scribed by other authors since the monographs were published have been added, and wherever new information on nuclear characters was available it is stated. I had hoped to be able to present with this a new classification of the Rissoidae, but the slowness attending the acquiring of certain material necessary to a complete understanding of the group has decided me not to withhold the manuscript longer, but to publish the data pertaining to members of that famil}'^ under the old familiar designation, reserving the necessary changes for the final revision. I wish to express my thanks to all the students who have con-tributed material to this study, acknoAvledgment for which is made under the various species. Credit is due to the photographic divi-sion of the United States National Museum for the splendid en-larged photographs of the species described, and to Mrs. E. B. Decker for the careful and painstaking work of perfecting these illustrations by retouching. PYRAMIDELLIDA (LONGCHAEUS) COOPERl Anderson and Martin. Plate 42, fig. 3. PyramideUa cooperi Anderson and Martin, Proc. Cala. Acad. Sci., ser. 4, vol. 4, 1914, p. 66, pi. 7, figs. 18a 18&. Shell elongate conic, stout, grayish white. All the early whorls decollated, the three remaining strongly channeled at the summit, flattened between the summit and the peripheral sulcus, angulated Proceedings U. S. National Museum. Vol. 52-2193. 637
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