Lamarck’s Genera of Shells. 71 
3. Terebella*. 
Body tubular, elongated, depressed, cylindrical, posteriorly 
attenuated ; very slight transverse annular segments; a single 
row of nodular and bristly mammille on each side. 
Numerous advanced, filiform, twisted tentacula terminate its 
anterior part, and surround the mouth; two rows of tufted 
ramose branchiz, disposed on one side below the tentacula. 
Tube elongated, cylindrical, attenuated and pointed at the 
base, membranous, with grains of sand and fragments of shells 
agglutinated round it; open only at the apex. 
Type. Terebella conchilegat. 
Tubes formed of the fragments of testaceous substances ; 
three branchiz on each side. Coast of Holland. PI. iii. Fig. 5. 
3 Species. 
4, Amphitrite. 
Body tubular, elongated, cylindrical, posteriorly attenuated, 
segments numerous; a row of bristly {mammille on each side ; 
bundles of crooked awl-shaped setz, on the border of a lamina. 
Two remarkable terminal branchie, divided into very slender 
digitations, disposed in the form of a fan, sometimes in that 
of a funnel, or expanded into a disc. Two short awl-shaped 
filaments inserted in the inner base of the branchie. Mouth 
subterminal, between the branchiz. ~ 
Tube elongate, cylindrical, posteriorly attenuated, membran- 
ous or coriaceous ; in most, externally naked. 
Type. Amphitrite ventilabrum t. (Sabella penicillus. Iinn.) 
Stems of the branchize very thin; branchie plumose, fan- 
shaped; body rather flattened. PI. iii. Fig.6. 6 Species. 
Serputa§. (5 Genera.) 
Branchize separate, or covered with an operculum. Tube 
solid and calcareous. 
1. Spirorbis |]. 
Body tubular, subcylindrical, posteriorly attenuated ; six 
pinnate, rectractile branchie, disposed in rays, at the anterior 
* A little auger. + Shell-gatherer, 
t A fan for winnowing. § From sevpo, to creep. 
|| From spira, and orbis, signifying a spiral orb. 
