310 ANNELIDA 



C. limnaei von Baer (Fig. 491). Anterior bundles of setae with 10 

 to 20 each; length 5 mm.: eastern states, usually found on Lymncea and 

 Planorbis or parasitic in their liver; also free-living; common; Europe. 



C. pellucidus Walton. Setae forked, 6 to 7 

 in a bundle; length 1.5 mm.: Cedar Point, Lake 

 Erie; common. 



FAMILY 6. TUBIFICIDAE. 

 limncei(S\issvf, F.'Deut.) 



Slender, red or brown worms living in fresh 



or brackish water in tubes from which they protrude the hinder end; 4 

 bundles of setae on each segment; testes and ovaries in segments 10 or 

 11; but 1 pair of sperm ducts; no reproduction by division; clitellum on 

 segments 11 and 12: about 14 genera and 50 species. 

 Key to the genera of Tubificidae here described : 



o x Dorsal setae both forked and hair-like 1. TUBIFEX 



a z Dorsal setae all forked. 



&! Setae of segment 11 modified 3. BOTHHIONEUEUM 



& 2 These setae not modified. 



<?! No blood capillaries in body wall 2. CLITELLIO 



c 2 Capillaries in body wall 4. LIMNODRILUS 



1. TUBIFEX Lamarck. Forked and usually hair-like setae in the 

 dorsal bundles; usually forked setae alone in the ventral bundles; con- 

 tractile hearts in segment 8: several species. 



T. irroratus (Verrill) (Clitellio irroratus Verr.). Pink or brown 

 worms 3 cm. long; prostomium acute: near high- water mark south of 

 Cape Cod on the seashore. 



T. benedeni Udekem. Gray or black worms ; cutie- 

 ula studded irregularly with flattened papillae; length 

 4 cm. : Long Island Sound to Maine, near high-water 

 mark on the seashore. 



T. tubifex (0. F. Muller) (Fig. 492). Reddish 



. , tae with middle 



worms about 4 cm. long with about 60 segments; the teeth (Stissw. F. 



forked setae in dorsal bundles in front of the clitellum 

 have 1 to 3 middle teeth; ventral setae all forked: in mud in standing 

 and running fresh water; often common, forming reddish patches on the 

 mud where they are seen waving their hinder ends in the water; Europe. 



2. CLITELLIO Savigny. Forked setae alone present; contractile 

 hearts in segments 8 and 9; no blood capillaries in body wall; prostate 

 glands diffuse: 1 species. 



C. arenarius (0. F. Muller) (C. irroratus Verrill). Body very slen- 

 der and reddish, up to 6 cm. long; setae sigmoid: Long Island Sound 

 to Maine, often very common under rocks and stones near high-water 

 mark on the seashore; Europe. 



