APPENDIX 199 
PHYLUM III. VERMES 
The lower worms. Animals of primitive structure and without 
paired locomotory appendages or distinct head. 
SuppHyitum I. Plathelminthes. Flatworms; no anus present in 
most forms and body-cavity filled with a vesicular connective tissue 
called parenchyma. 
Class 1. Turbellaria. Mostly free-living flatworms with ciliated 
outer surface. Ex. Planaria. 
Class 2. Trematodes. Flukes. Small parasitic flatworms with mostly 
a branched digestive tract and an anterior mouth. Ex. Fasciola. 
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 ciliated outer 
surface. Ex. Cerebratulus. 
SuppHyium IT. Nemathelminthes. Round or thread worms; mostly 
parasitic. Ex. Ascaris. 
Suspuyivm III. Trochelminthes (Rotifera). Minute, aquatic worms 
with mouth surrounded by cilia. Ex. Rotifer. 
Susppnytum IV. Bryozoa. Minute, sessile, colonial animals with 
a ridge bearing ciliated tentacles around the mouth. Ex. Bugula. 
SuBpHytum V. Brachiopoda. Sessile, marine, mollusk-like animals 
with a dorsal and a ventral shell. Ex. Terebratulina. 
Suppuyitum VI. Phoronidea. Sessile, marine worms living in tubes 
and with a tentacular ridge around the mouth. Ex. Phoronis. 
SuppHytum VII. Chaetognatha. Minute, transparent, marine 
worms with a slender body, two or three pairs of horizontal fins, 
and paired prehensile bristles around the mouth. Ex. Sagitta. 
SusppHytum VIII. Sipunculoidea. Elongated, marine worms, the 
anterior portion of which can be invaginated and is usually sur- 
rounded by tentacles. Ex. Sipunculus. 
PHYLUM IV. ANNELIDA 
The higher worms. Elongated, segmented worms which have 
paired, unsegmented appendages, and a usually distinct head. 
Class 1. Archiannelida. No parapodia or setw. Ex. Polygordius. 
