Document Type



Platyceras is a generic term which has been proposed for a Paleozoic group of mollusks whose shells are "sub-oval or sub-globose, with a small spire, the whorls of which are sometimes free and sometimes contiguous; the mouth generally campanulated or expanded." These fossil shells have been frequently referred to the genus of modern mollusca known as Capulus. In the case of Platyceras as in many other Paleozoic genera, numerous species have been based, not on any apparent distinctive character, but seemingly simply on their occurrence at different geological horizons; and this has given rise to the establishment of many species which are unquestionably invalid. For specific distinction considerable importance has been attached to the configuration of the peristome, but even this feature now appears to have little classificatory value in the majority of species of the genus. A careful comparison of a large series of different species of Platyceras reveals the fact that the apertural margin in various specimens of the same species often presents considerable variation: a phenomenon not to be entirely unexpected in a group so closely allied to the modern Capulus.

Publication Date


Journal Title

Proceedings of the Iowa Academy of Sciences




Pt. 2

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©1890 Iowa Academy of Science, Inc.



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