APPENDIX ^25 



Class 3. Cestodes. Tapeworms. Elongated, usually segmented para- 

 sitic flatworms without digestive tract. Ex. Taenia. 



Class 4. Nemertea. Nemertean worms. Elongated, mostly free- 

 swimming flatworms with a protrusile proboscis and a cilated outer surface. 

 Ex. Cerebratulus. 



SuBPHYLUM 11. Nemathelminthes. Roundworms or threadworms; 

 mostly parasitic. Ex. Ascaris. 



SuBPHYLUM III. Trochelminthes (Rotifera). Minute, aquatic worms 

 with mouth surrounded by cilia. Ex. Rotifer. 



SuBPHYLUM IV. Bryozoa. Minute, sessile, colonial animals with a ridge 

 bearing ciHated tentacles around the mouth. Ex. Bugula. 



SuBPHYLUM V. Brachiopoda. Sessile, marine, mollusk-like animals with 

 a dorsal and a ventral shell. Ex. Terebratulina. 



SuBPHYLUM VI. Phoronidea. Sessile, marine worms living in tubes and 

 with a tentacular ridge around the mouth. Ex. Phoronis. 



SuBPHYLUM VII. Chaetognatha. Minute, transparent, marine worms 

 with a slender body, two or three pairs of horizontal fins, and paired pre- 

 hensile bristles around the mouth. Ex. Sagitta. 



SuBPHYLUM VIII. Sipunculoidea. Elongated, marine worms, the an- 

 terior portion of which can be invaginated and is usually surrounded by 

 tentacles, Ex. Sipunculus. 



PHYLUM V. ANNELIDA 



The higher worms. Elongated, segmented worms which have paired, 

 unsegmented appendages, and a usually distinct head. 



Class I. Archiannelida. No parapodia or setae. Ex. Polygordius. 



Class 2. Chaetopoda. With setae, segmentally arranged. 



Order i. Polychaeta. Mostly marine chaetopods with parapodia on which 

 are numerous setae. Ex. Nereis. 



Order 2. Oligochaeta. Earthworms. Mostly fresh-water or land chaetopods 

 without parapodia and with few setae. Ex. Lumbricus. 



Class 3. Hirudinea. Leeches. Annelids with a sucker at each end and no 

 appendages or setae. Ex. Hirudo. 



Class 4. Myzostomida. Disk-shaped parasites of echinoderms with five 

 pairs of parapodia. Ex. Myzostoma. 



PHYLUM VI. ARTHROPODA 

 Externally segmented animals with segmented appendages. 



Class I. Crustacea. Aquatic, gill-bearing arthropods; two pairs of an- 

 tennae present. 



