SYLLIDAE. 165 



aa. Dorsal cirri present only on tlie first setigcrous somite Proceraslea Langerhans. 



AA. Ventral cirri present. 



B. Palpi not fused; cirri and tentacles articulated, moniliform Syllinae. 



a. Parapodia without branchial appendage. 

 6. Pharj'nx unarmed. 



c. Setae all simple; four (or three) minute eyes in a transverse row on each side. 



Synehnis, gen. nov. 

 cc. Composite setae present; two eyes on each side, these not in a transverse row. 

 d. Tentacles and notocirri entire, short and fusifonn and covered with papillae. 



RhopalosyUu Augener. 

 lid. Tentacles and notocirri moniliform and moderately long, not papillose. 



XenosyUis Marion et Bobretzky. 

 66. Pharynx armed. 



c. With a single large tooth. 

 d. Tooth anterior. 



e. Tentacular cirri present; first somite without setae .Sj//fe Savigny. 



ee. Tentacular cirri absent; first somite with setae Isosyllis Ehlers. 



dd. Tooth posterior Opisthosyllis Langerhans. 



cc. With a large tooth accompanied by a trepan, or with a trepan alone. 

 d. A large tooth accompanied by a trepan. 

 e. Cirri consisting of several articles. 



/. Setae all simple Trypanosyllis Claparede. 



ff. Anterior setae compound, others crochet-form, simple Synsyllis Verrill. 



ee. Cirri spherical, undi\aded Eurysyllis Ehlers. 



dd. A trepan alone. 



e. Notocirri jointed; neurocirrus stout and blunt, fused proximally with the parapodium; 



nuchal organs forming large "epaulettes" PtcrmMytus Ehlers. 



ee. Notocirri not jointed; neurocirrus flattened and pointed, not fused with parapodium; 



nuchal organs not conspicuously developed Parautolytus Ehlers. 



Bli. Palpi more or less fused. 



C. Fused only at base; cirri and tentacles usually simple and smooth, rarely in some degree 



articulated Eusyllinae. 



a. Pharyn.'C straight. 

 b. Pharynx unarmed. 

 c. With a large flap projecting from psristomium over pro.3tomium; tentacles tapering. 



Hespercdia Chamberlin. 



cc. With no such peristominal lobe; tentacles clavate Syllides Oersted. 



66. Pharynx armed, 

 c. With a large tooth. 



d. The tooth single, unaccompanied. 



e. Tooth posterior in position Opisthodonta Langerhans. 



ee. Tooth anterior Pioiwsyllis Malmgren. 



dd. The large tooth accompanied by an incomplete trepan of small teeth. 



e. Setae all simple HemisylUs Verrill. 



ee. Setae in part composite. 



/. Tentacles and cirri smooth Eusyllis Malmgren. 



ff. Tentacles and curi moniliform; palpi united to middle. .. .Desmosj/Wis Verrill. 

 fc. With a semicircle of large recurved corneous papillae or teeth. . . .Odonlosyllis Claparede. 

 aa. Pharynx sinuous. 



6. With no tentacular cirri; notocirri rudimentary Fauvelia Gravier. 



66. Tentacular cirri present; notocirri not rudimentary, 

 c. Unarmed. 



d. With only composite setae Campesyllis Chamberlin. 



dd. With both simple and composite setae Streptosyllis Webster & Benedict. 



cc. Armed with a large tooth and trepan; with nuchal flaps Amblyosyllis Grube. 



CC. Fused throughout length Exogoninae. 



a. With one pair of tentacular cirri. 

 6. Tentacular cirri rudimentary; appendages (tentacles and cirri) cylindrical; prostomium 

 distinct from the peristomiiun .Exogone Oersted. 



