78 DISCOVERY REPORTS 



— Body short, stout. Segments few. Filiform anal branchiae and a large ventral shield 

 bordered with stiif bristles Sternaspididae 



i8. Palps long, tentacle-like 19 



— No tentacle-like palps ... ... ... ... ■■• ■•• ■•• ••• ••• ... 22 



19. Two long tentacular palps on prostomium ... ... ... ... ... ... ... 20 



— One or more pairs of palps inserted on the anterior segments. Branchiae simple, filiform, 

 inserted above the feet. Capillary and usually acicular bristles. Prostomium conical 

 without processes Cirratulidae 



20. Two palps and two groups of branchiae retractile into a buccal funnel. Chaetae of first 

 feet prolonged forwards to form a cephalic cage. Body thickly papillated ... Chlorhaemidae 



— Two long grooved palps not retractile into the mouth. No cephalic cage ... 21 



21. Palps without suckers. Pedal lamellae erect. Dorsal branchiae cirriform. Hooded hooks 

 present Spionidae 



— Palps with sucker-like papillae. Without branchiae. Prostomium spoon-shaped 



Magelonidae 



— Anterior cirri flask-shaped or frilled. Lateral branchiae filiform. Several kinds of bristle 



Disomidae 



22. A single median tentacle. Dorsal cirri and foliaceous dorsal branchiae. Capillary bristles 

 and hooded hooks Paraonidae 



— Prostomium with or without two short tentacles. Parapodia more or less conspicuous. 

 Capillary bristles and forked bristles. No hooks Scalibregmidae 



— Prostomium blunt, without appendages or with a crown of laciniated lobes. No branchiae. 

 Ventral tori with many rows of minute uncini. Tube sandy Oweniidae 



— Prostomium with a keel or bordered cephalic plate. An anal plate or an anal funnel with 

 cirri. No branchiae. Dorsal bristles capillary, ventral sigmoid hooks ... Maldanidae 



23. A terminal branchial tuft with numerous filaments bearing secondary processes. Pro- 

 stomium indistinct. Uncini ventral in the thoracic region, dorsal in the abdominal region. 

 Tube membraneous or calcareous ... ... ... ... ... ... ... ... 32 



— Without terminal branchial tuft ... ... ... ... ... ... ... ... 24 



24. Large flattened chaetae (paleae) forming an operculum closing the tube 31 



— Without opercular bristles ... ... ... ... ... ... ... ... ... 25 



25. Prostomium conical or blunt, without processes. Branchiae on many segments 28 



■ — Prostomium more or less distinct. One pair of tentacle-like palps or numerous tentacular 



filaments ... ... ... ... ... ... ... ... ••• ... ... ... 26 



26. Prostomium with or without two small tentacles. Two long grooved palps. Two to three 

 markedly dissimilar regions, the anterior short with uniramous feet bearing special chaetae 



in 4th chaetiger. Posterior notopods erect. Uncini pectinate Chaetopteridae 



— Without tentacles. A cephalic veil and numerous tentacular filaments. Ventral tori with 

 pectinate uncini ... ... ... ... ... ... ... ... ... ... ... 27 



27. Tentacular cirri retractile into the mouth. Prostomium distinct. Three to four pairs of 

 branchiae inserted on the first segments ... ... ... ... ... Ampharetidae 



— Tentacular cirri not retractile. Prostomium indistinct. Branchiae arborescent or rarely 

 subulate, inserted on the first segments. Sometimes absent .. . ... ... Terebellidae 



28. With uncinigerous tori 30 



— Without uncinigerous tori 29 



29. Serrated capillary bristles and acicular hooks. Feet and branchiae conspicuous and erect 



on the back in the abdominal region ... ... ... ... ... ... ... Ariciidae 



— Capillary bristles only. Feet without lobes. Branchiae lateral, ligulate. Prostomium 

 pointed; conical ... Opheliidae 



30. Prostomium blunt. Anterior region abranchiate: middle with dorsal, arborescent, non- 

 retractile branchiae: often an achaetous and abranchiate caudal region ... Arenicolidae 



