Excerpt from Simpson's Unionid Types and Miscellaneous Unionid Types in the National Museum of Natural History

Simpson, while diligent in the locating and marking of Lea's types, was not always careful in the selection and pre servation of his own. Some are missing, and a number of them were never figured. That some were not figured is understandable, since, though they were intended, no illustrations accompanied the 1914 work. All of the measured unfigured types which could be located are figured here. In some cases it seemed desirable to select lectotypes when syntypes were available.

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