CONTENTS. 

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Page. 



Introduction 109 



I. Historical m 



II. Reproduction 114 



The marsupium 1 16 



Use of the marsupium in classification 116 



General structure of the marsupium 120 



Internal structure of the marsupium 125 



Phylogeny of the marsupium 135 



Conglutination of the embryos 136 



Stratification of unfertilized eggs 138 



Abortion of embrjos and glochidia 138 



Breeding seasons , 139 



Long period of gravidity 141 



Short period of gravidity 143 



III. The larva I45 



Structure of the glochidium 145 



The hookless type .' 146 



The hooked type i49 



The Proptera or axe-head type 150 



The larval thread 151 



Behavior and reactions of glochidia 152 



Reactions of hookless glochidia 153 



Reactions of hooked glochidia 155 



IV. The parasitism 156 



Artificial infection of fish 156 



Infections with hooked glochidia 158 



Infections with hookless glochidia 160 



Susceptibility of fishes to infection 162 



Behavior of fishes during infection 163 



Infection of fish in large numbers 164 



Conditions necessary- for successful infection 166 



Duration of the parasitic period 167 



Implantation and cyst formation 169 



Metamorphosis without parasitism in Sirophitus 171 



V. Attempt to rear glochidia in culture media 174 



VI. Post-larval stages 175 



Beginning of the growth period and life on the bottom 175 



Juvenile stages and the origin of mussel beds 177 



Rate of growth I79 



Growth of mussels in vrire cages 180 



An artificially reared mussel 182 



The origin and age of mussels in artificial ponds 184 



107 



