POLYCH^TA 



299 



2. Clymenella Verrill. Body with 18 or more setigeroiis segments 

 and with obliquely truncated head : several species, 2 in the Woods Hole 

 region. 



C. torquata (Leidy) (Fig. 472). Body with 

 a membranous collar arising near the middle of 

 the 4th setigerous segment; 22 segments, 18 with 

 setae; color reddish; length 10 cm.: North Caro- 

 lina to Bay of Fundy; in sand from low-water 

 mark to 60 fathoms. 



3. NiCOMACHE Malmgren. Funnel-shaped ter- 

 minal segment with marginal cirri; head without 

 truncating plate; prostomium sharply bent down- 

 w^ards: several species. 



N. lumbricalis (Fabricius). Body slender and 

 fragile, consisting of 26 segments; color pink; 

 length 7 cm.: Cape Cod and northwards; Europe. 



Fig. 472 — Clymenella 



torquata (Leidy). 



A, entire worm 



B, hinder end. 



Family 3. AEENICOLIDAE. 



Elongated worms which burrow deep in the sand; 

 head without appendages, with an unarmed proboscis; 

 peristomium with a pair of lithocysts; parapodia rudi- 

 mentary, with branching gills above them in the middle 

 of the body: 1 genus. 



Arenicola Lamarck. Anterior end blunt, the pro- 

 stomium and peristomium being fused together; body 

 cylindrical, thickest at the forward end: few species, 2 

 in tlie Woods Hole region. 



A. marina (L.) (Fig. 473). Segmentation indistinct, 

 the skin being annulated; about 21 setigerous segments 

 present, of which 8 compose the anterior and 13 the 

 middle region, but only 4 dissepiments and 6 pairs of 

 nephridia; length up to 20 cm.; diameter 8 mm.: Long 

 Island Sound northwards; in deep buiTows in the sand; 

 rare south of Cape Cod; Europe. 



A. cristata Stimpson. Head very small; middle 

 branchiate region with 11 pairs of gills; color greenish- 

 yellow; length 35 cm. or more: Florida to Cape Cod. 



Family 4. CHLOEH^MIDAE. (Fig. 452, F.) 



Eather small worms which live in burrows and under stones; body 

 not divided into regions; whole head retractile and with a circle of 3 to 



