26 Only the 4th pair of branchiae pinnate. Hooded hooks biden- 



tate. Prostomium square in front P. dayi 



26' First and 4th pair of branchiae pinnate. Hooded hooks multi- 

 dentate. Prostomium rounded in front 27 



27 A dorsal crest across setiger 7 or setigers 7 and 9 28 



27' No dorsal crest across setiger 7 or 9 P. fiteointnipi 



28 A dorsal crest across setiger 7 only P.fallax 



28' A dorsal crest across setiger 7, a low ridge across setiger 8, 



and a crest across setiger 9 P. criatata 



29 Prostomium without an occipital tentacle. [Branchiae free 



from notopodial lamellae and continue to posterior seg- 

 ments (Microspio). Prostomium with a brown patch. Hooded 



hooks from setiger 12 with 3-5 denticles above main fang] M. plgminitata 



29' Prostium with an occipital tentacle 30 



30 Prostomium rounded. Branchiae free from notopodial lamellae 



and absent from posterior segments. Membranous genital 



pockets between neuropodia of middle segments (Laonicv) L. cirruta 



30' Prostomium pointed. Branchiae fused to notopodial lamellae 

 in anterior segments but free later and continue to posterior 

 segments. No pockets between neuropodia (N( riHides). 

 [Hooded hooks unidentate] N. niikhnitata 



Polydora commerifiolis Andrews, 1891 



Piili/d<>)v cdDni/cusalis Andrews, 1891b: 291, pi. 

 15: Fig. 27. - Hartman, 1945: 32; 1969: 133. 

 Fig. 1-4. -Blake, 1969: 815, Fig.3; 1971: 17, 

 Fig. 11. - Foster, 1971: 20, Fig. 1-12. 



Rcconh. — Cape Hatteras area and Beaufort, 

 intertidal to a few meters (5, 6, 11, 18, 22) 



Dist)-ibiiti(>iL — Massachusetts to North Caro- 

 lina; Caribbean; Pacific Siberia to California and 

 western Mexico; intertidal to 30 m; commensal 

 with hermit crabs. 



Polydora ivebsteri Hartman, 1943 



Polydom caccu. - Webster, 1879: 252, pi. 9: 



Fig. 119-122 (n»u Oersted). 

 Polydora H'e6.s'fen Hartman, 1945: 33; 1951: 81; 



1969: 151, Fig. 1-5. - Blake, 1969: 814, Fig. 



2; 1971: 6, Fig. 3. - Foster, 1971: 26, Fig. 



30-36. 



Records. — Cape Hatteras to Beaufort, inter- 

 tidal and dredged (3, 5, 11. 13, 15, 18, 19, ? *). 



Distrihutio}!. — Newfoundland to Gulf of Mexi- 

 co; Oregon to Southern California; Hawaii; inter- 

 tidal to 100 m. 



Polydora caeca (Oersted. 1843) 



FiK-ure 10a-<i 



Polydora caeca. - P^iuvel, 1927: 52, Fig. 18 a-k. - 

 Day, 1967: 469. Fig. 18.3. e-h. 



Description. — Length up to 20 mm. Prosto- 

 mium notched in front and produced back as a 

 ridge to setiger 2. Four eyes. Setiger 1 with 

 notosetae. Fifth hooks (Figure 10a) plain and 

 unidentate. Gills from setiger 7-9 to middle of 

 body at least. Hooded hooks (Figure lOd) from 

 setiger 7. Specialized posterior notosetae (F'ig- 

 ure 10c) as two to four straight spines only 

 slightly stouter than accompanying capillaries 

 (F'igure 10b). Pygidium saucer-shaped.. Juveniles 

 with scattered pigment flecks on anterior seg- 

 ments. 



/?( »H«)7r.s'. — P. caeca is closely related to 

 P. sociali.'< and the small differences between 



68 



