306 



ANNELIDA 



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

 species. 



B. illuminatus (Moore) (Fig. 481). Body 4 mm. long and .9 mm. 

 wide, the head being composed of 4 segments, the trunk of 11, 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 the 

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

 the external (usually the ventral) surface of 

 crayfish; eastern and central North America. 



3. PTERODRILTTS 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. 



Fig. 481 



Bdellodrilus illuminatus 

 (Moore). 



Fig. 482 



Pterodrilus distichus 

 (Moore). 



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. ENCHYTKJEIDAE.* 



Fig 483 More or less slender worms 30 mm. or less in length 



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



F^eu^) 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 "Enchytrseidae of the West Coast of North America," by G. Eisen, Harrt- 

 man Alaska Exp., Vol., 12, 1910, 



