MANUAL OF NATUBAL HISTORY. 319 



the body ; eyes sessile on the neck ; mucous 

 glands on sides of body. Terrestrial. 



II. OKDER — Helminthoid- Annelids (Rhabdoccela), 



Alimentary tube simple, cylindrical or conical ; 

 oral aperture and anus variously disposed. 



I. SUB-ORDER. — Amphisteeeans (Amphisterea). 



Neither oral nor anal aperture terminal, but both 

 either superior or inferior. 



1. Family. — Turbellas (Vorticidse). Body gene- 



rally tapering, covered with vibratile cilia ; 

 eyes two or four. 



2. Family. — Leptoplanas (Leptoplanidse). Body 



depressed, membranaceous ; intestinal canal 

 simple ; eyes one or many, on the neck. 



II. SUB-ORDER.— Monostereans (Monosterea). 

 Oral or anal aperture terminal. 



3. Family. — Gordians (Gordiidse). Oral orifice ter- 



minal, anal inferior ; body tapering, filiform, 

 elastic, often coiled up in knots ; caudal ex- 

 tremity bifid ; eyes none. 



4. Family. — Short-tailed Worms (Micruridae). Oral 



orifice terminal, anal inferior ; body tapering, 

 filiform, elastic ; tail simple ; eyes six or more. 



5. Family. — Long -mouthed Worms (Derostomati- 



dse). Anal orifice terminal, oral inferior ; body 

 tapering ; eyes none. (Chilophorina, Ehrenb.) 



