Vlll CONTENTS 



PLATYHELMINTHES (Continued). PAGE 



NEMERTINEA 55 



Tetrastemma 55 



NEMATHELMINTHES 57 



Ascaris 57 



Trichina 58 



TROCHELMINTHES 60 



ROTIFERA 60 



Brachionus (A Rotifer) 60 



MOLLUSCOIDA 62 



POLYZOA 62 



Bugula 62 



Plumatella 64 



BRACHIOPODA 64 



Terebratulina 64 



ECHINODERMATA 66 



ASTEROIDEA 67 



Asterias (Starfish) 67 



OPHIUROIDEA 73 



Ophiura (Serpent-Star) 73 



ECHINOIDEA 74 



Strongylocentrotus (Sea-Urchin) 74 



HOLOTHUROIDEA 80 



Thyone (Sea-Cucumber) 80 



ANNELIDA 84 



CaETOPODA 85 



Nereis virens (Clam- Worm) 85 



Autolytus cornutus 89 



Polynce (Lepidonotus) squamatus 89 



Diopatra cuprea 91 



Chaetopterus 92 



Amphi trite ornata 93 



Pectinaria (Cistenides) gouldii 94 



Clymenella torquata 94 



Arenicola cristata 95 



Sabella microphthalma 95 



Hydroides 96 



Spirorbis borealis 96 



Lumbricus (Earthworm) 97 



Macrobdella (Leech) 102 



GEPHYREA 106 



Phascolosoma 106 



MOLLUSCA 109 



LAMELLIBRANCHIATA Ill 



Venus mercenaria (Quahog) Ill 



Yoldia limatula 119 



Mytilus or Modiola (Mussels) 121 



Pecten irradians (Scallop) 122 



Ostrea virginiana (Oyster) 123 



Solemya " 124 



Mya arenaria (Long Clam) 124 



Ensis directus (Razor-shell) Clam 125 



