84 PERCY SLADEN TRUST EXPEDITION 
presence of numerous colourless scalariform filaments. I have not seen any specimens, 
having an operculum with spines springing from the top of a truncated cone, as described 
by Gravier from Météore, but in more than one case specimens of Spirobranchus semperi 
and its variety acroceros have been collected and placed with this species. 
The wings on the peduncle are fringed on their upper free ends or quite plain as 
pointed out by Gravier (21) or there may be only a single filamentous process or the 
whole wing may be so reduced as to appear at first sight to be absent. The operculum 
is always carried on the left side and there is no secondary one. The interbranchial 
membrane may have a single cirrus between two adjacent gills or a much divided 
process. 
Length of specimens varies from 15 to 40 mm. and the width from 2—3 mm. 
The sete agree with those so beautifully figured by Gravier (21, text-figs. 482—487). 
The uncini, while much resembling Gravier’s figure in some directions, show a distinctly 
gouge-shaped anterior tooth (figs. 8@ and b); this is particularly clear in front view 
(fig. 8c), therefore I have ventured to include Gravier’s species, which I cannot imagine 
can be different from this, in the genus Spirobranchus. 
17. Spirobranchus maldivensis, n. sp. (Plate 9, fig. 9). 
Specific characteristics: 1. Operculum a thin calcareous plate, without processes, 
supported by a tall pedicle with thin lateral wings (fig. 9a). 2. Collar setee with a short 
wide finely striated fin-like process at the base of the narrow anterior blade (fig. 90). 
3. Branchize about 32 pairs with numerous long pinne except at their distal ends, which 
are bare and filamentous. 4. Thoracic uncini have about 15 teeth im addition to the 
large gouge-shaped one (figs. 9d and e) and the abdominal 13. 5. Abdominal setze 
narrow compressed trumpets with one side produced into a long process (fig. 9 /). 
Characteristics 1 and 2 separate this species widely from any other in the genus, in 
fact, 1b may at some later time be found advisable to establish a new genus for it. The 
collar setze are somewhat similar to those of Omphalopoma, Lang, and some other genera 
and the operculum is unusual in having no spines. 
Locality. ‘Three specimens in their tubes from Mulaku, Maldive Archipelago, Prof. 
Stanley Gardiner’s collection. 
Three tubes are fused together longitudinally and a fourth is firmly fused with a 
Gastropod (Yurritella?) shell. In the latter the small end of the shell at first sight 
appears to be a large pointed process overhanging the mouth of the Serpulid tube. Hach 
tube has one coarsely serrated ridge. Two of the specimens are 20 mm. long and 2 or 
3 mm. in their widest part; the other is 30 mm. long but not more than 2 mm. wide. 
The branchize are 7—8 mm. high and not spirally arranged. The collar is high, 
folded inwards along the median ventral line and interior to the dorso-lateral lobes are 
small folded lateral processes of the ventral lobe as in Spzrobranchus, &c. > 
The fascicles of collar setze are rather long and slender containing about 10 of the 
characteristic sete (9b) and about the same number of simple narrow blades (fig. 9c). 
All the other thoracic sete are simple blades. 
