The Miocene and Recent Mollusca of Panama Bay*

Abstract

The material studied has been in the Paleontogical collection, of Columbia University for several years. The label on the material reads as follows: Brought up by marine dredge from depths varying from ro.. ft. to 4°. ft. in the mud at the mouth of the Rio Grande near La Boca about one mile from the mainland in Panama Bay. It was apparently collected by Mr. Donald F. Mac Donald in ro7, formly Geologist of the Canal Commission, and sent by him to Columbia University. The material has been partially identified by Dr. J. J. Galleway and Mr. S. W. Lowman in 1923. I discovered that this collection is a mixture of Lower Miocene and Recent shells, for the collector was unable to keep them separate under the circumstances. The faunas of the two horizons which are separated and the relative abundance of each species are as follows:-