47G 
annelides. 
bundles of awl-sbaped bristles, in a single row on each side, 
and also hooked bristles; branchiae terminal, fan-shaped, and 
deeply cleft into pinnated, or plumose finger-like divisions; 
mouth terminal, placed between the branchiae, and surmounted 
by a pedicled funnel, or club-shaped operculum ; tube solid, 
testaceous, irregularly twisted, either grouped or solitary, fixed, 
with a rounded and terminal aperture. 
Serpula vermicular is .— The Vermicular Serpula. 
Plate XCII. tig. 14. 
White, cylindrical, tapering, rugged, variously curved and 
twisted. Inhabits the coasts of Britain. 
Genus 5.— SPIRORBIS.— Lamarck. 
Generic Character. —Body tubular, subcylindrical, posterior¬ 
ly attenuated; six pinnated, retractile branchiae, in radiated ex¬ 
pansions, at the anterior extremity; operculum placed between 
the branchiae; tube testaceous, spirally twisted into an orbicu¬ 
lar form, depressed and adhering below. 
Spirorbis Nautiloides .— The Nautilus-Shaped Spirorbis. 
Plate XCII. fig. 15. 
White, nautilus-shaped, transversely wrinkled. One-eighth of 
an inch in diameter. Inhabits the British coasts, on Algae, &c. 
TRIBE II.-AMPH1TRIT7EA. 
Branchiae not separate or covered by an operculum, and 
disposed anteriorly •, tube membranous, or horny, and more or 
less arenaceous. 
* With large branchiae or tentacula. 
Genus G.—AMPHITRITE.— Lamarck. 
Generic Character. —Body tubular, elongated, cylindrical, 
attenuated behind, with many annulated segments ; and a single 
row of setiferous papillae, fasciculated subulate bristles, and hook¬ 
ed setae; branchiae in slender finger-shaped fasciculi, disposed like 
a fan, and spreading into a disk ; two short subulate filaments 
inserted at the internal base of the branchiae, between which is 
