E-text prepared by deaurider, RichardW, and the Online Distributed Proofreading Team (http://www.pgdp.net) from page images generously made available by Internet Archive (https://archive.org) and HathiTrust Digital Library (https://www.hathitrust.org/) Note: Project Gutenberg also has an HTML version of this file which includes the original illustrations. See 58924-h.htm or 58924-h.zip: (http://www.gutenberg.org/files/58924/58924-h/58924-h.htm) or (http://www.gutenberg.org/files/58924/58924-h.zip) Images of the original pages are available through Internet Archive. See https://archive.org/details/crayfishintrodto00huxl The few pages missing are available through HathiTrust Digital Library. See https://catalog.hathitrust.org/Record/100319852 Transcriber's note: Text enclosed by underscores is in italics (_italics_). A caret character is used to denote superscription. A single character following the caret is superscripted (example: Lt^d). Small capitals have been converted to all upper case. Original printed page numbers are shown like this: {52}. Some characters might not display properly in this UTF-8 text file (e.g., empty squares). If so, the reader should consult the html version or the original page images noted above. THE CRAYFISH, AN INTRODUCTION TO THE STUDY OF ZOOLOGY BY T. H. HUXLEY, F.R.S. * * * * * * THE INTERNATIONAL SCIENTIFIC SERIES. Each Book Complete in One Volume. Crown 8vo. cloth, 5_s._ unless otherwise described. I. FORMS of WATER: in Clouds and Rivers, Ice and Glaciers. By J. TYNDALL, LL.D., F.R.S. With 25 Illustrations. Twelfth Edition. II. PHYSICS and POLITICS; or, Thoughts on the Application of the Principles of ‘Natural Selection’ and ‘Inheritance’ to Political Society. By WALTER BAGEHOT. Tenth Edition. III. FOODS. By EDWARD SMITH, M.D., LL.B., F.R.S. With 156 Illustrations. Tenth Edition. IV. MIND and BODY: the Theories of their Relation. By ALEXANDER BAIN, LL.D. With Four Illustrations. Ninth Edition. V. The STUDY of SOCIOLOGY. By HERBERT SPENCER. Eighteenth Edition. VI. The CONSERVATION of ENERGY. By BALFOUR STEWART, M.A., LL.D., F.R.S. With 14 Illustrations. Eighth Edition. VII. ANIMAL LOCOMOTION; or, Walking, Swimming, and Flying. By J. B. PETTIGREW, M.D., F.R.S., &c. With 130 Illustrations. Fourth Edition. VIII. RESPONSIBILITY in MENTAL DISEASE. By HENRY MAUDSLEY, M.D. Fifth Edition. IX. The NEW CHEMISTRY. By Professor J. P. COOKE, of the Harvard University. With 31 Illustrations. Eleventh Edition. X. The SCIENCE of LAW. By Professor SHELDON AMOS. Eighth Edition. XI. ANIMAL MECHANISM: a Treatise on Terrestrial and Aërial Locomotion. By Professor E. J. MAREY. With 117 Illustrations. Fourth Edition.