CONTENTS. 



Xlll 



Crustaceans (continued). Page 



Ciliary movement 174 



Eggs of Rotifera 175 



CIRRIPEDS. ORDER CIRRIPEDIA 177 



Remarkably constructed Limbs 177 



Their casting-net i7 8 



Divided into two Families 179 



Barnacles 179 



Acorn-Shells J79 



CHAPTER XIV. 



THIRD DIVISION OF INVERTEBRATE ANIMALS. 



MOLLUSKS, "Shell-Fish" 180 



Definition of Mollusks 180 



Heterogangliata 181 



CHAPTER XV. 

 FIRST CLASS OF MOLLUSKS. 



POLYZOA 184 



Sea-Mats 184 



SearMoss 185 



Aviculariae 186 



Fluviatile Polyzoa 187 



CHAPTER XVI. 



SECOND CLASS OF MOLLUSKS. 



TUNICARIES. TUNICATA l88 



Ascidians 189 



Beauty and delicacy of their internal 



structure 189 



Salpians 189 



Pyrosoma, its dazzling splendour 190 



Compound Ascidians 191 



CHAPTER XVII. 



THIRD CLASS OF MOLLUSKS. 



ORDINARY BIVALVES. CONCHIFERA 192 



Scallop, its structure 192 



Its Mantle, Gills, Mouth, and Hinge ... 192 

 Elaborate mechanism of the Gill-fringe.. 192 

 Classification of Conchifera 195 



First Family Oysters 195 



Common Oyster 195 



Tree-Oyster 195 



File-Shells 195 



Scallops 196 



Pearl-Shells 196 



Pearl Oyster Pearl fishery 196 



Second Family Mussels 197 



Their Foot, its use's 197 



Pinna, Byssus 197 



True Mussels 197 



River-Mussels, sometimes enclose Pearls 197 



Third Family Clams.... 198 



Clam-Shells '.. 198 



Giants of the Bivalve race 198 



Strength of their Byssus 199 



Fourth Family Cockles 199 



Common Cockle, its Foot a wonderful 

 organ 199 



Mollusks (continued). Page 



Fifth Family Inclusa 200 



Razor-Shells 201 



Stone-borers, their excavations 201 



Pholades, their Dens 202 



Their tools for boring 202 



Teredo, its destruction of submarine 

 woodwork.... .. 202 



CHAPTER XVIII. 

 FOURTH CLASS OF MOLLUSKS. 



BRACHIOPODA, their arms 203 



Contrivance for procuring food 204 



CHAPTER XIX. 



FIFTH CLASS OF MOLLUSKS. 



GASTEROPODA 204 



Why so called 204 



Different Orders of, how distinguished... 205 



ORDER PULMONIFERA 206 



Air-breathing Gasteropods 206 



Terrestrial, how recognizable 206 



Slugs 206 



Snails 207 



ORDER PECTIMBRANCHIATA 207 



Aquatic Air-breathing Gasteropods 207 



Their Operculum or door 207 



Their Eyes on Footstalks 208 



Curious Egg-cases 209 



Wentle-trap 209 



Legend of the Origin of the Tyrian dye. 212 



Its changes of Colour 212 



Stromb-Shells 212 



ORDER TUBULIBRANCHIATA 213 



Their Tube-shell and door 213 



ORDER SCUTIBRANCHIATA 213 



Keyhole Limpets 214 



ORDER TECTIBRANCHIATA 214 



For the most part naked Slugs 214 



Sea-Hares 214 



ORDER INFEROBRANCHIATA 215 



ORDER CYCLOBRANCHIATA 215 



Limpets 216 



Coat-of-Mail Shell, Chiton 216 



ORDER NUDIBRANCHIATA 216 



Naked-gilled Mollusca common on the 



British coast 216 



Their great diversity and beauty of form 217 



Homed Doris 217 



Tritonia Hombergi 217 



Young of Nudibranchiate Gasteropods... 217 



ORDER HETEROPODA 218 



Their fin-shaped Foot used as an Oar ... 218 



CHAPTER XX. 

 SIXTH CLASS OF MOLLUSKS. 



ORDER PTEROPODA 219 



Their locomotive apparatus 219 



Northern Clio, its instruments of pre- 

 hension 220 



Limacina helicina, its exquisite Shell ... 220 



Hyalsea 221 



Cleodora, its luminosity 221 



