264 ESSENTIALS OF ZOOLOGY 



Phylum VIII. Echinodermata (Starfish, Sea Urchin, Etc.) 



Class I. Asteroidea 



Order 1. Phanerozonia — Astropecten 

 Order 2. Spinulosa — Solaster 

 Order 3. Forcipulata — Asterias 



Class n. Ophiuroidea 



Order 1. Ophiurae — Ophioderma 

 Order 2. Euryalae — Gorgonocephalus 



Class III. Echinoidea 



Order 1. Cidaroida — Eucidaris 



Order 2. Centrechinoida — Arhacia 



Order 3. Clypeastroida — Clypeaster 



Order 4. Spatangoida — Moira 



Class IV. Holothuroidea 



Order 1. Actinopoda — Thyone 



Order 2. Paractinopoda — Leptosynapta 



Class V. Crinoidea — Antedon 



Phylum IX. MoUusca (Clams, Snails, Etc.) 



Class I. Amphineura 



Order 1. Polyplacophora — Chiton 

 Order 2. Aplacophora — Neomenia 



Class II. Pelecypoda 



Order 1. Protobranchiata — Nucula 



Order 2. Filibranchiata — Mytilus 



Order 3. Eulamellibranchiata — Lampsilis 



Order 4. Pseudolamellibranchiata — Ostrea 



Class III. Gastropoda 



Order 1. Prosobranchiata — Helicinia 

 Order 2. Opisthobranchiata — Aplysia 

 Order 3. Pulmonata — Helix 



Class IV. Scaphopoda — Dentalium 



Class V. Cephalopoda 



Order 1, Tetrabranchiata — Nautilus 

 Order 2. Dibranchiata — Loligo 



Phylum X. Arthropoda (Insects, Crustacea, Etc.) 



Class I. Crustacea 



Subclass A. Branchiopoda 



Order 1. Phyllopoda — Branchipus 



Order 2. Cladocera — Daphnia 

 Subclass B. Ostracoda — Cypris 

 Subclass C. Copepoda — Cyclops 

 Subclass D. Cirripedia — Balanus 

 Subclass E. Malacostraca 



Order 1. Nebaliacea — Nehalia 



Order 2. Anaspidacea — Anaspides 



Order 3. Mysidacea — My sis 



Order 4. Cumacea — Diastyli,$ 



