Penciled memoranda on the Unionidae; descriptions, illustrations, ecology, contents of his cabinet and geographical localities of this group of shells. Includes some opinions of other scholars, some listings from cabinets of others and some specimens collected by conchologists in various scattered parts of the world.

Name of donor not known, but notebooks were in the Conchology Department of the Academy for some time before being archived. H. A Pilsbry's note is inserted in notebook no. 1, “Memoranda on Unionidae, Isaac Lea. Better preserve for their historic interest.”