||The Northern portion of the extensive area now embraced under the name Laramie Group was the first to attract attention. It was natural that the earliest transcontinental voyages should follow the larges water-ways, and notwithstanding the extremely slow development of the Upper Missouri River region we find that its exploration was begun in the first decade of the last century by parties provided with appliances for scientific observation and has been continued at intervals ever since. Leaving the merely geographical aspects out of the account, we find that the coal beds attracted the attention of Lewis & Clarke in 1803 and of every subsequent expedition down to the epoch of true geological investigation, which dates from the commencement of the protracted researches of Meek and Hayden in the year 1854. the investigations of Harris & Audubon in 1844 added scarcely anything to the knowledge of the geological age of these regions. As much might be said of the explorations of Fremont, who observed the lignite beds of Wyoming in 1842, and of the expedition of General Emery, who noted those of Eastern New Mexico in 1848. But the large collections brought by Hayden from Nebraska and the upper Missouri and Yellowstone regions in 1854, furnish the data for profitable scientific investigation, which they soon received a the competent hands of Meek and Leidy.