viii CONTENTS 



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Pond-Snails (Viviparidce) Valvatidce Ampullariidce Cydophoridce Cyclostomatidce 

 TruncatellidceHipponychidceCalyptrceidce XenopJwridce Naticidce Section Pteno- 

 (jlossa Violet Snails (lanthinidce) Wentle-Traps (Scalariidce) Section Gymnoglossa 

 Eulimidce Pyramidellidce Suborder Heteropoda Pterotracheidce Atlantidce Sub- 

 order Scutibranchiata Section Rhipidoglossa Helicenidce Neritidce Turbinidce- 

 Trochidce Delphinulidce Ormers (Haliotidce) Pleurotomariidce Keyhole Limpets 

 (Fissurellidce) Section Docoglossa Acmceidce Limpets (Patellidce) Lepetidce, . . 341 



CHAPTER XI. MOLLUSCS, concluded. Classes Amphineura, Scaphopoda, and Pelecypoda. 



The Chiton Group (Class Amphineura) Chitons (Order Polyplacophora) Order Aplacophora 

 The Tooth-Shells (Class Scaphopoda) The Bivalves (Ckss Pelecypoda) Order Proto- 

 branchiata Order Filibranchiata Order Pseudolamellibranchiata Order Eulamelli- 

 branchiata Suborder Submytilacea Suborder Tellinacea Suborder Veneracea Sub- 

 order Cardiacea Suborder Myacea Suborder Pholadacea Suborder Anatinacea 

 Order Septibranchiata, . .... .398 



CHAPTER XII. MOSS-ANIMALS AND LAMP-SHELLS, Subkingdom Molluscoidea. 



The Moss- Animals (Class Bryozoa) Characteristics of the Group Subclass Ectoproda Order 

 Phylactolcemata Order Gymnolaemata Subclass Entoprocta The Lamp-Shells (Class 

 Brachiopoda) and their Characteristics Hinged Group (Order Testicardines) Hinge- 

 less Group (Order Ecardines\ ... . . 419 



CHAPTER XIII. THE WORM-LIKE ANIMALS, Subkingdom Vermes. 



Characteristics of Worms Bristle-Worms, or Annelids (Class Annelida) Their Distinctive 

 Features Many-Bristled Group (Order Polychceta) Sparsely-Bristled Group (Order 

 Olicjoch(Eta)1\\Q Leeches (Class Hirudinea) The Gephyrean Worms (Class Gephyrea) 

 The Wheel- Animalcules (Class Rotifera) The Thread-Worms, or Round-Worms (Class 

 Nematohelminthes) Spiny-Headed Thread-Worms (Order Acanthocephala) Typical 

 Thread-Worms (Order Nematoidea) Arrow-Worms (Order Chcctognatha) The Nemer- 

 tine Worms (Class Nemertinea) The Flat- Worms (Class Platyhelminthes) Tape- 

 Worms (Order Cestoda) Trematode Worms (Order Trematoda) Many-Suckered Group 

 (Suborder Polystomece) Two-Suckered Group (Suborder Distomece) Turbellarian 

 Worms (Order Turbellaria) Suborder Ehabdoccela Suborder Dendroccela Group of 

 Uncertain Position (Orthonectidce and Dicyemidce), ..... 43i 



CHAPTER XIV. JELLY-FISH, CORALS, AND SEA-ANEMONES, Subkingdom Codenterata. 



Distinctive Features of Ccelenterates The Ctenophores (Group Ctenophora) Stinging Series 

 (Group Cnidaria) The Jelly-Fish and their Allies (Class Polypomedusce) Order 

 Siphonophora Order Hydromedusce Fresh- water Forms Order Scyphomedusce The 

 Sea- Anemones and Corals (Class Anthozoa) Six-Rayed Polyps (Order Hexactinid) 

 Horny Corals (A niipatharia) Eight-Rayed Polyps (Order Odactinia) Coral-Reefs and 

 Islands, . ..... . 474 



CHAPTER XV. THE SPONGES, Subkingdom Porifera. 



Distinctive Characters of the Group Reproduction The Calcareous Sponges (Class Calcarea) 

 Six-Rayed, or Glass-Sponges (Class Hexactinellida^Tlie Common Sponges (Class 

 Demospongia) Four-Rayed Sponges (Order Tetractinellida) - The Fleshy Sponges 

 (Order Carnosa) Single-Rayed Sponges (Order Monaxonida) Fresh-Water Sponges 

 Horny Sponges (Order C&ratosa), . . 526 



