350 MANUAL OF NATURAL HISTORY. 



tail of the female, producing a kind of hermaphro- 

 ditism of a most remarkable description. 



V. CLASS.— CAVITARY-PARASITES 



(Coelelmintha.) 



Alimentary canal distinct, tubular, with an oral 

 and an anal orifice ; mouth without radiating ten- 

 tacles ; body elongated, cylindrical, not divided into 

 segments ; sexes distinct. Parasitic in other ani- 

 mals. 



1. Family. — Proboscidean -Worms (Liorhynchida3.) 



Mouth terminal, obtuse, emitting a simple 

 retractile proboscis ; body elongated, cylin- 

 drical, elastic, tapering posteriorly. 



2. Family. — Spiniferous-Worms (Cheiracanthidae.) 



Oral aperture terminal, bivalve, simple ; head 

 beset with simple spines ; body cylindrical, 

 elastic, armed at fore-part with palmate 

 spines ; tapering posteriorly ; tail of male 

 spiral ; spiculum simple. 



3. Family. — Hooded-Worms (Cucullanidse.) Anal 



aperture terminal ; head or neck covered 

 with a plicate or striated hood ; body elon- 

 gated, cylindrical, obtuse anteriorly, atten- 

 uate posteriorly ; tail of males straight, point- 

 ed, without a bursa at hind end. 



4. Family. — Star-mouthed Worms (Strongylidse.) 



Oral aperture ample, orbicular, surrounded 

 by teeth, papillae, or cilia ; body elastic, cy- 

 lindrical, tapering anteriorly ; tail of males 



