April 24th; Analytical Table of the Species of Hydroporus Found in the United States, with Descriptions of New Species; Synopsis of the Lathridiides of the United States, and Northern Contiguous Territories; Notes Derived from Observations Made on the Birds of New Mexico during the Years 1853 and 1854; Analyses of the Meteoric Iron from Tuczon, Province of Sonora, Mexico; Notice upon the Viviparous Fishes Inhabiting the Pacific Coast of North America, with an Enumeration of the Species Observed; Descriptions of New Species of Birds from Western Africa, in the Collection of the Academy of Natural Scienceses of Philadelphia; Notice of Remarkable Strata Containing the Remains of Infusoria and Polythalamia in the Tertiary Formation of Monterey,