MANUAL OF NATURAL HISTOEY. 351 



ending a styliferous bursa, and with a single 

 or double spiculum. 



5. Family. — Hermaphrodite-Worms (Syngamida3). 



Oral aperture terminal ; body moderate, sub- 

 cylindrical; male animal organically blended 

 with female by its caudal extremity. 



6. Family. — Round -Worms (Ascarididse). Oral 



aperture terminal, small, covered and con- 

 cealed by three rounded valvular lips ; body 

 cylindrical, elongated, tapering at each end. 



7. Family.— Slender-headed Worms (Triehocepha- 



lidae). Oral aperture very small, punctiliform, 

 at the end of a very slender non-retractile 

 peduncle or neck ; body elongated, cylindri- 

 cal posteriorly, gradually thickened and cla- 

 vate. 



8. Family. — Larval- Worms (Amblyuridae.) Oral 



aperture orbicular, simple or cirrhate ; body 

 cylindrical, elastic, sometimes free and na- 

 tant ; head continuous with body ; tail subu- 

 late, acute or obtuse. Parasitic in aquatic 

 larvae, or found in stagnant water. 



9. Fam:ily. — Guinea-Worms (Filariidso.) Oral aper- 



ture terminal, small, orbicular ; body cylin- 

 drical, filiform, of the same thickness through- 

 out, often very long and rigid, extremities 

 obtuse. Parasitic in the skin of man. 



POLYPS. 



These plant-like animals, sometimes known under 



