CLASSIFICATION 



673 



Class Mammalia 



Animals of Uncertain Position: 



Phylum Nemertinea 

 (Ribbon worms) 



Phylum Trochelminthes 

 (Wheel animals) 



Phylum Brachiopoda 

 (Lamp shells) 



Phylum Bryozoa 



(Moss animals) 



Phylum Chaetognatha 

 (Arrow worms) 



Phylum Gastrotricha 



Warm-blooded; hair; mammary glands (horses, whales, 

 bats, man) 



Circulatory system; proboscis; complete digestive tract 

 ( Lineus ) 



Smallest of the Metazoa; mostly fresh-water (rotifers) 



Marine; live within a calcareous, bivalve shell 



Mostly marine; resemble hydroids in form, but more ad- 

 vanced internally 



Marine; bilaterally symmetrical; consists of head, trunk, 

 and tail 



Fresh and salt water; body elongate and flexible with 

 forked tail. 



