Smithsonian Institution. United States National Museum. Bulletin

In the vicinity of Tampa Bay, Florida, and especially on the northwestern shores of the bay, near Ballast Point, are found certain limestones more or less mingled with layers of clay, marl, and chert, with residual sands and so-called "fuller's earth." This work attempts to illustrate some of these fossil materials.

The bats of the genus Myotis, though small and inconspicuous mammals, present many features of unusual interest from the point of view of systematic zoology. At nearly every point in its excessively wide range the genus is represented by several species often puzzlingly alike in superficial appearance though readily distinguishable from each other when the true differential characters are once recognized.

The North American recent mammals in the United States National Museum number about 166,000 specimens, including 1,435 types. More than three-fourths of this material is in the Biological Survey collection, United States Department of Agriculture, the remainder, including the seals, sirenians, ceataceans, and all of the older, more historic specimens, is in the Museum proper. The material derived from these two sources furnishes so complete a representation of the mammals of North America that, of the 2,554 forms now recognized, only 171 are not included.