TABULAR SURVEY OF CHIEF CLASSES. 



17 



METAZOA NON-CHORDATA. 



f Cephalopoda. Cuttle-fishes. 

 MOLLUSCA. "{ Gasteropoda. Snails. 



^ Lamellibranchiata. Bivalves. 



/"Arachnoidea. Spiders, scorpions, mites. 

 I Insecta. 

 Akthropoda. -\ Myriopoda. Centipedes and millipedes. 

 I Prototracheata. Peripatus. 

 ^Crustacea. 



(Crinoidea. Feather-stars. (Cystoids and Blastoids, extinct.) 

 Ophiuroidea. Brittle-stars. 

 Asteroidea. Star-fishes. 

 Echinoidea. Sea-urchins. 

 Holothuroidea. Sea-cucumbers. 



' Worms." 



CCELENTERA. 



PORIFERA. 



fChaetopoda. 

 (Discophora. 



Bristle worms. \ Annelids or 

 Leeches. ) Annulates. 



c Brachiopoda. Lamp-shells. 



\ Polyzoa, e.g. Sea-mat {Flustret). 



V Sipunculoidea, e.g. Sifunculus. 



Nematoda. Thread-worms. 

 Nemertea. Ribbon-worms. 



f Cestoda. Tape-worms. ^ 

 \ Trematoda. Flukes. j-Platyhelminthes. 



* V Turbellaria. Planarians. ■* 



{Ctenophora, e.g. Beroe. 

 Scyphozoa. Jelly-fishes and sea-anemones. 

 Hydrozoa. Zoophytes and medusoids. 



Sponges. 



PROTOZOA. 



Infusoria. Rhizopoda. Sporozoa. 

 Simplest forms of animal life. 



