OLIGOCH^TA 



309 



Fig. 488 

 Stylaria 

 lacustris 

 (Walton). 



2. STYLARIA Lamarck. Prostomium very long and tentacle-like; 

 setae as in Nais : 2 species, in Europe and America. 



5. lacustris (L.) (Fig. 488). Length 15 mm., with 25 segments: 

 common; Europe. 



3. PARANAIS Czerniavsky. Head distinct; setae all 

 forked; dorsal setae begin on segment 5; no eyes: 3 

 species. 



P. litoralis (0. F. Miiller) (Enchytr&us triventralo- 

 pectinatus Minor). Length 10 mm.; segments about 20; 

 blood greenish-yellow: Long Island and Vineyard Sounds, 

 under stones or decaying vegetation near high-water mark 

 on the seashore, also in fresh water; often very common; 

 Europe. 



4. DERO Oken. Setae as in Nais; ciliated branchial 

 appendages extend from the funnel-shaped rear end; 

 blood reddish; no eyes: 15 species, 4 in America; often 

 in tubes. 



D. limosa Leidy. Length 12 mm. or less with about 

 48 segments; color reddish: in tubes at the bottom of stagnant pools 

 and among algae; common; Europe. 



D. obtusa Udekem. Length 10 mm. ; a long and a short seta in each 

 dorsal bundle: Illinois; Europe. 



D. vaga Leidy (Fig. 489). Length 8 mm.; 

 number of segments 25 to 35; body ending in 2 

 long finger-like processes: often very common. 

 5. PRISTINA Ehrenberg. Dorsal setae all 

 hair-like and begin in second segment; ventral 

 setae all forked; prostomium very long and re- 

 tractile; rear end sometimes with long projec- 

 tions; no eyes: 8 species, 3 American. 



P. leidyi Smith. Length 8 mm., diameter .15 

 mm., with about 30 segments; 3 setae in each 

 dorsal bundle, 5 to 9 in each ventral bundle; 

 clitellum on segments 7 to 9 : in streams and lakes 

 in the eastern and central states; common. 



P. serpentina Walton (Fig. 490). Length 2.2 

 mm. with about 22 segments; dorsal bundle with 

 5 to 9 setae, ventral bundle with 5 or 6: very common; Cedar Point, 

 Lake Erie. 



6. CHJETOGASTER von Baer. Very transparent worms with 2 bundles 

 of hooked setae on the ventral side of each segment and no dorsal setae; 

 blood colorless : 6 species, 5 American. 





Fig. 489 



Fig. 490 



Fig. 489 

 Dero vaga (Walton). 



Fig. 490 



Pristina serpentina 

 (Walton). 



