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18 Operculum bell-shaped, lacks a central hollow, its proximal part 
swollen, distally bears a comparatively small number of, about 
17, broad, rounded, radial lobes with thick translucent cuticle; 
tubercles absent; a sharp constriction between operculum and 
peduncle . Serpula amplilobata n.sp. 
-Operculum has other forms. 19 
19 Operculum an elongated funnel bearing distally numerous 
sub-triangular radial lobes with blunt tips; tubercles present 
along radii; lacks a sharp constriction between operculum and 
peduncle . Serpula jukesii Baird, 1865 
-Operculum has other forms. 20 
20 Operculum funnel-shaped, its distal part circular, bearing 
numerous sub-triangular marginal lobes with blunt tips and thin 
transparent cuticle; tubercles absent along radii; proximal part 
like an inverted cone, decreasing in diameter posteriorly, then 
becoming bulbous before it joins the peduncle; a sharp constriction 
between operculum and peduncle. Serpula nudiradiata n.sp. 
Operculum funnel-shaped, possesses a central hollow; distally 
a moderately large number, up to about 30, bluntly triangular to 
squarish marginal lobes, with thin translucent cuticle; proximal 
part of operculum swollen; a sharp constriction present between 
operculum and peduncle . Serpula watsoni Willey, 1905 
21 Opercular processes consist of 8 consist of 8 conspicuously long 
spines, each bearing a row of, usually 3 or 4, somewhat elongated, 
pointed, unbranched, medial spines, with their tips medially curved, 
and short unbranched lateral spines, which may, in turn, bear 2 
or 3 smaller spines; at their centre is a very short, dichotomously 
branched horn; opercular plate circular . Spirobranchus baileybrockae n.sp. 
Operculum has other forms 
22 
22 Opercular processes usually consist of a pair of horns borne 
on a common base and arising posteriorly from the opercular 
plate; each horn bears a short bifid dorsomedial spine towards 
its base, a short posterolateral spine towards its middle, and ends 
in a bifid tip; latter often wasted through abrasion against tube; 
opercular plate oval, wider anteriorly than posteriorly .. Spirobranchus corniculatus (Grube, 1862) 
Operculum has other forms 
23 
23 Opercular processes consist of a pair of bluntly conical processes 
arising from opercular plate, and inclined posterodorsally; opercular 
plate circular . Spirobranchus sp. 1, cf. polytremus (Philippi, 1844) 
Operculum has other forms 
24 
24 Opercular processes consist of a short and stout or comparatively 
longer and less stout column bearing distally a pair of dorsolateral 
horns and a ventromedian horn; each dorsolateral horn ends in 
an anteroventrally curved, more or less pointed tip; dorsolateral 
horns not dichotomously branched; a short spine occurs at angle 
between ventral and each dorsolateral horn; its tip is directed 
towards the opercular plate; tips of bifid midventral process also 
curved opercular plate; each dorsolateral horn also bears 3 short 
accessory spines, one ventrolaterally towards its middle, the other 
two subterminally; opercular plate circular. Tube colour ranges 
from yellowish to yellowish brown and light mauve; in latter mauve 
patches on a white background. Spirobranchus richardsmithi n.sp. 
Operculum has other forms. 25 
