306 



ANNELIDA 



Fig. 481 



Bdellodrilus iUuminatus 



(Moore). 



2. Bdellodrilus Moore. Two pairs of testes and sperm ducts: 2 

 species. 



B. iUuminatus (Moore) (Fig. 481). Body 4 mm. long and .0 mm. 

 wide, the bead being composed of 4 segments, tbe trunk of Jl, all being 



biannulated ; clitellum is the dorsum of segment 

 6: often common on the gills of crayfish; co- 

 coons also on the gills ; eastern North America. 

 B. philadelphicus (Leidy). Head tbe 

 broadest part of the body ; length 10 mm. : on 

 the external (usually the ventral) surface of 

 crayfish; eastern and central North America. 



3. Pterodeilus Moore. Two pairs of testes and sperm ducts; long 

 paired, dorsal appendages on certain of the body segments: 2 species. 



P. distichus Moore (Fig. 482). 

 Dorsal appendages not branched; 

 length 1 mm. : on the external sur- 

 face of the crayfish in western 

 New York. 



Family 3. HAPLOTAXIDAE. , . . ^ p.^ ^gg 



Pterodrilus distichus 



Body very long and slender or "^^ ^ 



filamentous; setae sigmoid, single 



or paired, in 4 rows ; 2 pairs of ovaries ; central blood vessel contractile : 

 2 genera and 3 species. 



Haplotaxis Hoffmeister. Clitellum on segments 11 

 to 14 ; 2 pair male pores on segments 11 and 12 : 2 species. 

 H. gordioides Hartmann {H. emissarius Forbes) (Fig. 

 483). Dorsal setae absent on the hinder four-fifths of 

 body; length 18 cm. and more; width .6 mm.; 375 seg- 

 ments: in wet ground or in the water (Illinois; Phila- 

 delphia). 



Family 4. ENCTHYTRiEIDAE.* 



Fig. 483 

 Haplotaxis 

 gordioides 



(Siissw. 

 F. Deut.). 



More or less slender worms 30 mm. or less in length 

 which live in fresh water along the shore of the sea or in 

 decaying or living plants; setae hair-like, in 4 bundles in 

 each segment; clitellum when fully developed occupies 

 segments 11 to 13; dorsal blood vessel arises near the clitellum; testes 

 and ovaries in segments 11 and 12: about 13 genera and 170 species. 



• See "Enchytraeldae of the West Coast of North America," by G. Eisen, Harri- 

 man Alaska Exp., Vol. 12, 1910. 



