Proefschrift--Utrecht. / "Dit proefschrift is slechts een gedeelte van een grooter werk, dat onder den titel 'Die Heteropoden der Siboga-Expedition' binnenkort, als aflevering van de Résultats de l'Expédition du Siboga, het licht zal zien." Each plate is accompanied by leaf with descriptive letter-press. Text in German. Caption title: Die heteropoden der Siboga-expedition.

In August 1959 Pacific Marine Station (P.M.S.) located at Dillon Beach, began a program of oceanographic study as a member of the California Cooperative Oceanic Fisheries Investigations (C.C.O.F.I.). The program continued throughout the summer of 1963 and consisted of a monthly hydrographic station and sampling the plankton at the head of Bodega Submarine Canyon, located twenty-five miles west of Bodega Bay. Two plankton tows were taken on each ocean run. One of the samples, along with collection and hydrographic data, was sent to Scripps Institute of Oceanography. The other sample was retained at P.M.S. and constitutes the material for the present study. Pelagic gastropods were present in every tow in varying numbers and species. Two groups, pteropods and heteropods, were found in the samples. One species of pteropod, Limacina helicina, was the dominant member in all of the tows and occurred during the entire year. Little work has been done on the pelagic gastropods of the North Pacific. The information available has been mainly compiled by Tesch in the Dana Reports and McGowan (1960). Taxonomically the group has been extensively studied, but little is known about the life cycles, size ranges, growth rates, physiology, behavior, distribution and abundance. No previous study on the pelagic gastropods collected by P.M.S. has been made. This paper is a discussion of the pelagic gastropods collected over a period of four years. It is the purpose of this study to identify, examine, and present information of the local specimens collected by Pacific Marine Station.