Figure 10. Spionidae head composition. A, B in Origin of the pointed snout in Scolelepis and the mouth region in spionid polychaetes (Annelida: Spionidae)

Figure 10. Spionidae head composition. A, B, Paraprionospio sp., anterior ends, leħ lateral view. C, Aonides mayaguezensis Foster 1969, anterior end, ventral view. D, same, leħ lateral view, palps missing. E, F, Poecilochaetus trilobatus Imajima 1989, anterior end, fronto-ventral view, palps missing. Abbreviations: do, dorsal ciliated fold; lp, lateral peristomial lip; pa, palp; pr, prostomium; sh, basal sheath on palp; s1, s2, segments 1, 2; tu, prostomial tubercle; vp, ventral peristomial lip. Scale bars: A, B, E, F, 100 µm; C, D, 50 µm. A, B, North Carolina, USA (USNM 64109). C, D, Carrie Bow Cay, Caribbean Sea, Belize (USNM 1459211). E, F, Peter the Great Bay, Sea of Japan, Russia (USNM 1022171).