KEY TO FAMILIES 77 



2. Elytra on a certain number of feet, the rest bearing cirri 3 



— No elytra ^ 



3 . Compound bristles present Sigalionidae 



— No compound bristles ... ... ... ... ••• ••• ••• •■■ ••• ••■ * 



4. Never more than one segment bearing a dorsal cirrus intercalated between two elytrigerous 

 segments. Thread glands present in the feet Polyodontidae 



— In the hinder region of the body either all segments carry dorsal cirri or there are at least 

 two cirrigerous segments intercalated between two elytrigerous segments (except in 

 Lepidastheniella). No thread glands 5 



5. Eyes stalked, rarely sessile. A single tentacle. Facial tubercle conspicuous 



Aphroditidae 



— Eyes sessile. Three tentacles (except in Macellicephala, Bylgia and Iphione). Facial 

 tubercle absent or rudimentary .. . ... ... ... ... ... ... Polynoidae 



6. A fan-shaped group of broad flattened bristles (paleae) on all segments . . . Chrysopetalidae 

 Dorsal paleae absent ... ... ... ... ■-. ... •■• ••• ••• ■■■ 7 



7. Prostomium with two divergent tentacles and flanked by long cirri inclosing acicula. 

 Feet biramous without cirri or bristles Tomopteridae 



— Prostomium without tentacles. Feet uniramous. Bristles present 8 



— Prostomium with tentacles. Feet biramous ... ... ... ... ... ... ... 10 



8. Prostomium distinct, conical. Foliaceous dorsal and ventral cirri. A few acicular bristles 



Typhloscolecidae 



— Prostomium indistinct ... ... ... ... ... ... ... ... ... ••• 9 



9. Body papillated and bearing in addition transverse rows of large spherical capsules 



Sphaerodoridae 



— No such papulation. Cirri globular Pisionidae 



10. Prostomium small. Five tentacles. Caruncle usually present. Gills well developed. 

 Pharynx unarmed Amphinomidae 



— Prostomium large... ... ... ... ... ... ... ... ... ... ... 11 



1 1 . Pharyngeal armature complex. Upper jaws composed of a number of denticulated plates 



EUNICIDAE 



— Pharyngeal armature simple or absent. Tentacles not more than three ... ... ... 12 



— Tentacles more than three ... ... ... ... ... ... ... ... ... 14 



12. Palps simple. Pharynx armed with a single tooth or a crown of denticles, and followed 



by a barrel-shaped muscular gizzard. Feet uniramous ... ... ... ... Syllidae 



— Palps biarticulate, sometimes absent. No gizzard. Pharynx armed or unarmed ... ... 13 



13. Dorsal cirri of moderate length, not moniliform. Pharynx with a pair of toothed jaws and 

 almost always with numerous small paragnaths. Feet usually biramous ... ... Nereidae 



— Dorsal cirri long, moniliform. Pharynx cylindrical, unarmed or armed only with stylets 

 (except in A/ocra/za). Feet biramous and sesquiramous ... ... ... Hesionidae 



14. Prostomium conical, annulated, ending in four small tentacles. Pharynx papillated and 

 armed with at least four teeth. Feet biramous ... ... ... ... Glyceridae 



— Prostomium more or less rectangular with four small tentacles. Feet biramous, with 

 lamellae and a sickle-shaped gill between the rami. Pharynx usually with a pair of jaws and 

 rows of papillae. Bristles simple ... Nephthydidae 



— Feet with foliaceous cirri, without sickle-shaped gill, usually uniramous 15 



15. A pair of enormous globular eyes at the sides of the head ... ... ... Alciopidae 



— Eyes small, normal Phyllodocidae 



16. Body divided into distinct regions 23 



— Body not divided into distinct regions ... 17 



17. Segments numerous. Without anal branchiae and ventral shield 18 



3-2 



