Pp. xi, 290; numerous black-and-white plates (mostly photos), line-drawings, family trees. Publisher's original gray cloth, lettered in gilt on the spine and blind-stamped on the front cover, sm 4to. Presents 14 chapters by noted authorities in the field. These papers were originally presented in a symposium at the Linnean Society in London on September 9-10, 1975. No ownership marks and no signs of use.