Evolutionary Biology, of which this is the twenty-first volume, continues to offer its readers a wide range of original articles, reviews, and com­ mentaries on evolution, in the broadest sense of that term. The topics of the reviews range from anthropology and behavior to molecular biology and systematics. In recent volumes, a broad spectrum of articles have appeared on such subjects as evolution of the bacterial genome, biochemical system­ atics in plants, a discussion of species selection, and development and evolution of the vertebrate limb. Articles such as these, often too long for standard journals, are the material for Evolutionary Biology. The editors continue to solicit manuscripts on an international scale in an effort to see that everyone ofthe many facets of biological evolution is covered. Manuscripts should be sent to anyone of the following: Max K. Hecht, Department of Biology, Queens College of the City University of New York, Flushing, New York 11367; Bruce Wallace, Department of Biology, Virginia Polytechnic Institute and State University, Blacks­ burg, Virginia 24061; or Ghillian T. Prance, New York Botanical Garden, Bronx, New York 10458.