Pillai: Serpulid polychaetes from the Australian Kimberleys 
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Figure 59. A-H, Spirobranchus sp. 5. (A) an entire worm; opercular horns are damaged but rest of the body is intact; shows unfringed 
peduncular wings, inter-radiolar membranes unfringed or bearing a single papilla; abdominal neurochaetae with long shafts projecting 
beyond body wall and anal segment bearing a pair of papillae; ( B ) lateral view of the opercular plate and horns of another specimen; 
dichotomies apparently similar to that of S. kuwaitensis , as also is the spine preceding the second dichotomy, which is directed towards 
the centre of the opercular plate; (C) operculum and spines viewed from anterior end: opercular spines, dichotomies, and form and sizes 
of the lateral spines are quite different from those of Spirobranchus semperi Morch, 1861, (Fig. 56C,D); shows the fissures along the 
main branches of the opercular spines; ( D ) operculum and spines, and radioles, viewed from the anterior end; shows fissures along the 
main branches, and the medial spines. The inter-radiolar membranes possess only a single insignificant papilla; ( E) branchial radioles: 
showing inter-radiolar membranes bearing single papillae; (F) operculum of a juvenile worm viewed from below, showing the presence 
of a central hollow in the opercular plate, and the unfringed peduncular wing. G,H, bayonet-shaped special collar chaetae: (G) an abraded 
chaeta showing its squarish boss; ( H) a chaeta showing partly abraded boss, but is otherwise similar to G; blade in both abruptly tapered 
and only slightly longer than the serrated distal end of chaetal shaft plus boss. 
