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Dentalium. Tube testaceous, nearly regular, slightly curved, gradually 

 tapering towards the posterior end, open at both extremities. 



D. elephantinum, D. octoganum, D. entalis, D. nigrum, 



' aprinum, ' novcm costatum, ' tarentinum, ' politum, 



' fasciatum, ' dentalis, ' corneum, ' eburneum. 



AMPHITRITEA.— Four Genera. 



Pectinaria. Tube membranous or papyraceous, arenaceous, in shape of 

 a reversed cone, not fixed. 



P. bclgica, P. capensis. 



Sabellaria. Tubes numerous, united in a common mass, composed of 

 agglutinated fragments of shells and sand; the orifices cup-shaped. 



S. alveolata, S. crassissima. 



Terebella.. Tube elongated, cylindrical, attenuated and pointed at the 

 base; membranous, with grains of sand and fragments of shells adhering round 

 it; open only at the apex. 



T. conchilega, T. cranulata, T. duplicata, T. vittata, 



1 cristata, ' dimidiata, ' myuros, ' lineolata, 



' ventricosa, ' muscaria, ' lanceata, ' elongata. 



' maculata, \ ' oculata, ' aciculina, 



Amphitrite. Tube elongated, cylindrical; posterior extremity attenu- 

 ated, membranous or coriaceous; the exterior generally naked. 



A. ventilabrum, A. magnifica, A. volutacornis, A. infundibulum. 



' penicillus, ' vesiculosa, 



SERPULA.— Five Genera. 



Spirorbis. Tube testaceous, turned into an orbicular spire, discoidal; 

 the lower surface flat and fixed. 



S. nautiloides, S. carinata, S. lamellosa, S. tricostalis. 



' spirillum, 



Serpula. Tubes solid, calcareous, irregularly twisted, grouped or soli- 

 tary, fixed; the aperture terminal, round, very plain. 



S. vermicularis, S. infundibulum, S. intorta, S. costalis, 



' fasicularis, ' annulata, ' cristata, ' dcntifera, 



' intestinum, ' cereolus, ' spirukea, ' sipho, 



