This study originated in the attempt to identify a number of Rhynchotremas and Zygospiras from the Plattin and Decorah formations of Ste. Genevieve County, Mo. Comparisons were made with sets from several other localities in the Mississippi valley, and thus considerable additional material was examined, involving not only Black River horizons, but the Kimmswick and Maquoketa as well.
Proceedings of the Iowa Academy of Science
©1922 Iowa Academy of Science, Inc.
Fenton, Carroll Lane and Fenton, Mildred Adams
"Some Black River Brachiopods from the Mississippi Valley,"
Proceedings of the Iowa Academy of Science, 29(1), 67-83.
Available at: https://scholarworks.uni.edu/pias/vol29/iss1/10