CONTENTS. XV11 



Avicula margaritiferaA. frimbriata A. sterna Pearl 

 Fishery Details, etc. Pearls of Mytilus edulis Ano- 

 dontes Unio pictorum Unto margaritiferus Culture of 

 the Fresh-water Pearl-Mussel Value of its Pearls- 

 Artificial modes of causing it to produce Pearls Pinna 

 Their Silky Byssus and its uses Their Pearls Other 

 uses of Shells Tunicata and Bryozoa . . 135 198 



CHAPTER VIII. 

 WOKMS. 



Curious Observations upon Worms Eeproductive Power 

 oftheJVoJfs Sabularia Terebella Lumbricus Planar ia 

 Helminthes, or Entozoa The Common Earth-worm, 

 Lumbricus terrestris The Leech, Hirudo medicinalis 

 The Horse-leech, H. sanguisuga " Hirudiculture," or 

 Leech-breeding Its Cruelties Extent to which it is 

 carried in France Barometers of Leeches and Frogs 

 Worms for the Aquarium .... 199 210 



CHAPTER IX. 

 POLYPES. 



General Eemarks on Polypes Their Organization and Poly- 

 pidom Naturalists who have written upon Polypes 

 Hydra fusca and H. viridis Eeproduction of Polypes 

 Polypes for the Aquarium Corallium nobilis and general 

 Observations on Coral Its Polypidom Practical 

 Details concerning Coral " Coralliculture " Coral 



