PIXELL—POLYCH ATA OF THE INDIAN OCEAN 71 
each species the characteristics on which I have based my conclusions in identifying 
specimens. Doubtless it will be found necessary to emend some of these characteristics 
when more is known, for there can of course be no certainty with regard to the validity of 
any one characteristic for systematic purposes. 
Where not otherwise stated, the specimens are in Mr Crossland’s collections and the 
quotations as to colour of living specimens, &c. are from his notes. 
Genus Serpuna, Linné (81) 1767; Philippi (40) 1844. 
Generic characteristics: 1. Collar setae bayonet-shaped, with spines at base of blade. 
2. Opereulum funnel-shaped, with numerous radii ending in serrations on margin. 
3. Uncini with only a few teeth. 
1. Serpula vermicularis, Linné, 1767. 
Tubus vermicularis, Ellis (17) 1755. 
Serpula echinata, Gmelin (20) 1789; imbutiformis and infundibulum, Chiaje (10) 
1825; contortriplicata, Savigny (47, p. 73) 1826; fascicularis, Lamarck (80) 1838 ; 
aspera and pallida, Philippi (40) 1844; vermicularis and philippi, Mérch (387) 1863 ; 
narconensis, Baird (2) 1864; octocostata, Quatrefages (42) 1865; crater, Claparéde 
(12) 1870; patagonica, Grube (23) 1877; narconensis var. magellanica, M’Intosh 
(32) 1885. 
_ The above list includes the authors who originally gave the synonyms. For lists of 
those who followed them consult Mérch, 1863 (87) and Saint-Joseph, 1894 (44). 
Specific characteristics: 1. Collar setze with generally two large blunt processes at 
base of blade. 2. Uncini generally have five teeth; there may be 4—-7. 3. Branchie 
(20—32 pairs) long, with numerous pinne and bare filamentous extremities. 4. Serra- 
tions on operculum vary very much in number ; there may be as many as 100. 5. Maxi- 
mum length recorded is 50 mm. with 157 segments. 
Previously known distribution: Atlantic, Mediterranean, English Channel, North Sea, 
Magellan Strs., Marian Is., Orkney Is., Burdwood Bank, Table Bay. 
Localities. Several specimens from Jambiani on the under sides of stones; a few 
Specimens (2—3 cm. long) dredged in Wasin Channel, 7—10 fathoms; three small 
specimens from the bottom of SS. Juba lying off Zanzibar; also a few specimens from the 
Red Sea (Suakin?). Mr Crossland collected several other specimens from Porto Praya, 
Cape Verde Islands. 
The largest specimen of all, measuring slightly over 40 mm., came from Diamant 
Island, Peros Banhos Atoll, Chagos Archipelago. 
Nearly all possible variations in tube are to be met with, and there is also extreme 
diversity in the arrangement of the red colour markings on operculum, branchiz, thoracic 
membrane, &c. These variations have however already been described by Saint-Joseph 
(44), Fauvel (18), &c., and it is unnecessary to mention them here. Some specimens are 
undoubtedly in an immature state and show so few as 18 pairs of gills and 16 serrations 
on the edge of the operculum—some of the uncini have only four teeth. In these and 
