American natural historian, explorer, and educator. Graduated from Andover Theological Seminary, 1858. Ordained in the Presbyterian ministry, 1860. Instructor in natural history, University of Rochester, New York, 1866. Leader, Andes and Amazon expedition, 1867–9, 1873, 1876. Professor of natural history, Vassar College, 1869–77. Wrote a textbook on comparative zoology and published on women’s education.