Intestine trilobed, one lobe anterior to pharynx and two posterior, 

 with simple or branched diverticula 

 Suborder HAPLONEURA (or Paludicola) 



Aquatic; intestine lobes usually with branched diverticula 

 Suborder DIPLONEURA (or rerricola) 



Terrestrial; diverticula simple-branched 

 (Phylum) NEMERTEA (sometimes regarded as a class under Phylum 

 Platyhelrmnthes) 



With an eVersible proboscis above the anterior part of the digestive 

 tract; epidermis ciliated; anus present; no external segmentation 

 (Class) HOPLONEMERTEA 



Proboscis partly eversible, armed with one or more dagger-like 

 stylets 

 Phylum NEMATHELMINTHES 



Cylindrical animals with no external segmentation; ectoderm covered 

 with a thick cuticle; no cilia 

 Class NEMATODA 



With lengthwise, internal, lateral, muscular ridges; digestive tract 

 functional in most but not all families 

 Class GORDIACEA {or Tiematomorpha) 



No lateral, muscular ridges; digestive tract non-functional and often 

 incomplete in adult 

 Phylum ANNELIDA (or Coelhelminthes) 



Segmented or metameric externally and internally: with coelom, or 

 body cavity 

 Class POLYCHAETA 



With parapodia and setae 

 Class OLIGOCHAETA 



With setae but no parapodia 

 Class HIRUDINEA 



No parapodia or setae; with a sucking disc around the mouth and 

 usually another at the posterior end of the body; with more external 

 rings than true segments 



KEY TO THE PHYLA OF WORM-LIKE AND LEECH-LIKE ANIMALS 



L Animals minutely ciliated; moving with a gliding or flowing motion 2. 



Animals not ciliated (often with setae or bristles) ; usually moving with 



a writhing or hitching motion 3. 



2. Mouth, from which a long proboscis may be protruded, situated at the 

 anterior end; digestive tract tubular, running the length of the body; 

 getting to be three-quarters of an inch long; color reddish 

 NEMERTEA — one species in fresh water 



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