310 ANNELIDA 



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

 to 20 each ; length 5 nun. : eastern states, usually found on Li/mncea 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. 



Fig. 491-Ch<,togaster FAMILY 6. TUBIFICIDAE. 



Zjm«a?i(Sussw, 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 : 



Oi Dorsal setae both forked and hair-like 1. Tubifex 



Go Dorsal setae all forked. 



hi Setae of segment 11 modified 3. Bothrioneurum 



62 These setae not modified. 



Cj No blood capillaries in body wall .2. Clitellio 



Cj 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 

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

 Cape Cod on the seashore. 



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

 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. Miiller) (Fig. 492). Reddish tlu/ef^v^^i^Z 



-, , A -, i, 1 . ^^ , ., tae with middle 



worms about 4 cm. long with about 60 segments; the teeth (Siissw. 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. Foi-ked 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. Miiller) {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. 



