378 BIOLOGY 



Phylum VII. ANNULATA: the segmented worms. 

 Class I. Chcetopoda: bristle-footed worms. 



Sub-class A, Polychceta; with many bristles (Fig. 149). 



Sub-class B, Oligochceta ; with few bristles (Fig. 74). 

 Class II. Hirudinea: leaches. 

 Class III. Archiannelida. 

 Class IV. Gephyrea. 

 Class V. Choetognatha. 



Phylum VIII. MOLLUSCA. 



Class I. Pelecypoda or Lamellibranchia: bivalves, clams 



oysters, mussels. 



Class II. Gasteropoda: univalves, snails. 

 Class III. Amphineura: many-valved: chiton. 

 Class IV. Cephalopoda: with long arms: squids, cuttle 



fishes. 



Phylum IX. ARTHROPODA: with jointed feet. 



Class I. Crustacea: crabs, lobsters, barnacles. 



Class II. Onychophora. 



Class III. Myriopoda: millipedes, centipedes. 



Class IV. Hexapoda: insects. 



Class V. Arachnida: spiders, scorpions, etc. 



Phylum X. CHORD ATA: animals with a notochord. 



Sub-phylum, Atriozoa : body cavity opening to the exterior. 



Class I. Urochorda: tunicates or sea-squirts. 



Class II. Cephalochorda: amphioxus. 

 Sub-phylum, Vertebrate: animals with a vertebral column. 



Class. I. Pisces: fishes. 



Class II. Amphibia: frogs, toads, salamanders. 



Class III. Reptilia: lizards, snakes, turtles, alligators. 



Class IV. Aves: birds. 



Class V. Mammalia: mammals. 



