INDEX. 



581 



Third Class of Mollusca continued. 



First Family Oysters .... 



Common oyster 



Tree oyster ..... 



File-shells 



Scallops . 



Pearl shells ..... 



Pearl oyster pearl fishery . 

 Second Family Mussels 



Their foot, its uses .... 



Pinna, byssus ..... 



True mussels ..... 



River mussels, sometimes enclose pearls 

 Third Family Clams .... 



Clam shells ... 



Giants of the bivalve race . 



Strength of their byssus 

 Fourth Family Cockles 



Common cockle, its foot a wonderful organ 



Inclusa ...... 



Razor shells . ... 



Stone-borers, their excavations . . 



Pholades, their 1 dens .... 



Their tools for boring .... 



Teredo, its destruction of submarine wood-work 



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CHAPTER XVII. 



Fourth Class of Mollusca : 

 Brachiopoda, their arms 

 Contrivance for procuring food 



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CHAPTER XVIII. 



Fifth Class of Mollusca : 



Gasteropoda .... 

 Why so called . 



Different orders of, how distinguished 

 Air-breathing gasteropods . 

 Terrestrial, how recognisable 



Slugs 



Snails 



Aquatic air-breathing gasteropods. 



Their operculum, or door 



Their eyes on footstalks 



Curious egg-cases 



Wentle-trap .... 



Legend of the origin of the Tyrian dye 



Its changes of colour . 



Stromb-shells .... 



Tubulibranchiata 



Their tube-shell and door . 



Scutibranchiata, sea-ears 



Keyhole limpets 



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