CONTENTS.

PREFACE • v

LIST OF WOODCUTS • xi

CHAPTER I. The Natural History of the Common Crayfish • 1

CHAPTER II. The Phys­i­ol­o­gy of the Com­mon Cray­fish. The Mech­a­nism by which the Parts of the Liv­ing En­gine are sup­plied with the ma­terials nec­es­sary for their main­te­nance and growth • 46

CHAPTER III. The Phys­i­ol­ogy of the Common Crayfish. The Mechanism by which the Liv­ing Or­ga­nism adjusts it­self to sur­round­ing con­di­tions and re­pro­duces it­self • 87

CHAPTER IV. The Mor­phol­o­gy of the Com­mon Cray­fish. The struc­ture and the de­vel­op­ment of the in­di­vi­dual • 137

CHAPTER V. The Com­par­a­tive Mor­phol­ogy of the Cray­fish. The struc­ture and the de­vel­op­ment of the Cray­fish com­pared with those of other liv­ing beings • 227

CHAPTER VI. The Dis­tri­bu­tion and the Ætiol­ogy of the Cray­fishes • 288

NOTES • 347

BIB­LI­OG­RAPHY • 357

INDEX • 363