Pillai: Serpulid polychaetes from the Australian Kimberleys 
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Figure 51. A-G, Spirobranchus sp. 4: BMNH 1969.256. (A) dorsal view of the operculum a specimen, showing the double row of numerous 
papillae on the peduncular wing, and a bryozoan on the base of the opercular horns; ( B ) another specimen, the whole worm. The opercular 
plate is somewhat asymmetrical in this specimen. The inter-radiolar membranes are fringed, and the abdominal neurochaetae possess long 
shafts projecting beyond the abdominal wall; (C) another view of the operculum of the worm figured in B. Note that there are only two 
main dichotomies, the single long spine curved towards the centre of the group of horns, and the double row of numerous papillae along 
the peduncular wing; ( D ) another view of the same operculum of specimen figured in B. Note the somewhat elliptical opercular plate, the 
fringed peduncular wings, and the fringed inter-radiolar membranes; ( E ) a peduncular wing showing the double row of papillae; (F,G) 
bayonet chaetae that have been worn out; the former is worn out at its tip, and the latter, in the serrated part of the shaft preceding the boss. 
Chaetae. Older bayonet-shaped special collar chaetae may 
possess abraded blades (Fig. 51F,G), whereas the blades of 
those newly formed within the collar fascicles are not abraded 
(Fig. 52A). In the latter, the boss is squarish; a long part of 
the shaft preceding the boss is serrated, nearly equal to the 
length of the blade and the blades end in tapering tips; an 
unserrated notch is absent. Thoracic uncini bear 8-12 teeth in 
a single row, and the anterior gouged process; abdominal tori 
lateral (Fig. 5 IB) anterior abdominal uncini possess 7-9 teeth 
and an anterior gouged process. Abdominal neurochaetae 
possess flattened trumpet-shaped tips, one side drawn out into 
a tapered process, and with long shafts projecting from their 
