Encyclopedias useful for Biology

 TITLE        Van Nostrand's scientific encyclopedia / Douglas M. Considine,
                editor ; Glenn D. Considine, managing editor.
 EDITION      8th ed.
 PUBLISHER    New York : Van Nostrand Reinhold, c1994.
 Science Library-Reference      Q121 .V3 1994
 (also in Leyburn Reference)
 TITLE        McGraw-Hill encyclopedia of science & technology : an
                international reference work in twenty volumes including index.
 EDITION      7th ed.
 PUBLISHER    New York : McGraw-Hill, 1992.
 Science Library-Reference      Q121 .M3 1992  (20 vols)
 (also in Leyburn Reference)

 TITLE        Encyclopedia of human biology  [edited by] Renato Dulbecco.
 PUBLISHER    San Diego : Academic Press, 1991.
 Science Library-Reference      QP11 .E53 1991 (8 vols)

 TITLE        Magill's survey of science. Life science series / edited by Frank
                N. Magill, consulting editor, Laura L. Mays Hoopes.
 PUBLISHER    Pasadena, Calif. : Salem Press, c1991.
 Science Library-Reference      QH307.2 .M34 1991  (6 vols)
And Encyclopedia Britannica Online is often worth a look as well.