POLYCH^ETA 



295 



Key to the genera of Terebellidae here described: 



d Worms not filamentous ; branching gills present. 

 6j Three pairs of branching gills present. 



GI Capilliform setae only on anterior somites 1. AMPHITRITE 



c a Capilliform setae also on posterior somites 4. LEPILEA 



Z> 2 Two pairs of branching gills. 



c x Capilliform setae begin on segment 4 2. PISTA 



C 2 Capilliform setae begin en segment 3 5. THELEPUS 



5 3 But 1 gill, which has 4 branches 3. TEBEBELLIDES 



a z Worms filamentous and blood red ; no branching gills. / 



& x Parapodia simple 6. POLYCIRBUS 



6 2 Parapodia elongated and branched 7. ENOPLOBBANCHUS 



1. AMPHITRITE 0. F. Miiller. Body cylindrical, thickest towards 

 the forward end; 3 pairs of branching gills; setae begin on the 4th seg- 

 ment and confined to anterior part of body; no eyes: many species, 4 

 in the Woods Hole region. 



A. ornata (Leidy) (Fig. 469). Color pinkish; length up to 30 cm., 

 with about 40 setigerous segments; tentacular filaments very long, nu- 

 merous, and contractile: North Carolina to 

 Cape Cod, at low-water mark; common, living 

 in firm tubes which are sometimes cast up on 

 the beach. 



A. brunnea (Stimpson). Color dark red- 

 dish-brown; segments about 100, 25 of which 

 have setae; each gill with 7 to 12 branches; 

 length up to 18 cm.: north of Cape Cod at 

 low-water mark, in deeper water towards the 

 south. 



2. PISTA Malmgren. Two pairs of branch- 

 ing gills; setae begin on the 4th segment and 

 extend to the 20th; no eyes; first 3 somites 

 with large ventral and lateral wings : 3 species 

 in the Woods Hole region. 



P. palmata (Verrill). Body rather slen- 

 der, with 17 setigerous segments ; color reddish- 

 brown; length 7 cm.; width 2 mm.; animal constructs tubes of bits of 

 shell, etc.: Long Island and Vineyard Sounds. 



3. TEREBELLIDES Sars. Two pairs of gills present which are 

 large and form 4 wide, comb-like branches on a single peduncle; ten- 

 tacular filaments numerous (over 100) : 1 species in the Woods Hole 

 region. 



T. strcemi Sars. Body with about 60 segments and reddish in color; 

 length 7 cm.; width 5 mm.: Vineyard Sound to Bay of Fundy; in 10 

 to 250 fathoms; Europe. 



Fig. 469 



Amphitrite ornata (Verrill). 



1. tentacular filaments 



2, gills. 



