SYLLIDAE. 105 



aa. Dorsal cirri present only on tlie first sotigcrous somite Procerasfei Langerhans. 



A A. Ventral cirri present. 



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



a. Parapodia without branchial ai)pendage. 

 h. Pharynx unarmed, 

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



Synelmis, gen. nov. 

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

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



Rhopalosyllis Augoncr. 

 (Id. Tentacles and notocirri moniliform and moderately long, not papillose. 



Xcnosyllis Marion et Bobretzky. 

 bb. Pharynx armed. 



c. With a single large tooth. 

 d. Tooth anterior. 



e. Tentacular cirri present; first somite without setae t9?/iKs Savigny. 



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



dd. Tooth posterior Opiaihosyllis 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. 



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



ee. Cirri spherical, undivided Eurysyllis Ehlers. 



dd. A trepan alone. 



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



nuchal organs forming large "epaulettes" Pleraulolylus P^hlers. 



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



nuchal organs not conspicuously developed Parautolytus Ehlers. 



BB. Palpi more or less fused. 



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



articulated Eusyllinae. 



a. Pharynx straight. 

 b. Pharynx unarmed. 

 c. With a large flap projecting from psristomium over prostomium; tentacles tapering. 



Hesperalia Chamberlin. 



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



hb. Pharynx armed, 

 c. With a large tooth. 



d. The tooth single, unaccompanied. 



c. Tooth posterior in position Opisthodonta Langerhans. 



ee. Tooth anterior Pionosyllis Malmgren. 



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



e. Setae all simple Ilemisyllis Verrill. 



ee. Setae in part composite. 



/. Tentacles and cirri smooth Eiisyllis Malmgren. 



ff. Tentacles and cirri moniliform; paljii united to middle .... De.swo.s?///i.s Verrill. 

 cc. With a semicircle of large recurved corneous papillae or teeth. . . .Odordosyllis Clai)arede. 

 aa. Pharynx sinuous. 



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



bb. Tentacular cirri present ; notocirri not rudimentary, 

 c. Unarmed. 



d. With only composite setae Campesyllis Chamberlin. 



dd. With both simple and composite setae Sireptosyllis 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. 

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

 distinct from the peristomium Exogone Oersted. 



