August 29th; Descriptions of New Fishes, Collected by Dr. A. L. Heermann, Naturalist Attached to the Survey of the Pacific Railroad Route, under Lieut. R. S. Williamson, U. S. A; Enumeration of the Species of Marine Fishes, Collected at San Francisco, California, by Dr. C. B. R. Kennerly, Naturalist Attached to the Survey of the Pacific R. R. Route, under Lieut. A. W. Whipple; Observations upon a Collection of Fishes Made on the Pacific Coast of the United States, by Lieut. W. P. Trowbridge, U. S. A., for the Museum of the Smithsonian Institution; Synopsis of Extinct Mammalia, the Remains of Which Have Been Discovered in the Eocene Formations of Nebraska; Notice of a New Genus of Cyprinidœ; Synopsis of the Erotylidæ of the United States; Descriptions of New Fossil Species from the Cretaceous Formation of Sage Creek, Nebraska, Collected by the North Pacific Railroad Expedition, under Gov. J. J. Stevens; Descriptions of New Fossil Species from the Fresh Water Tertiary Formation of Nebraska, Collected by the North Pacific Railroad Expedition, under Gov. J. J. Stevens