GENERA OF SHELLS. 5 



with grains of sand and fragments of shells 

 adhering ; open at apex only. 



T. conchilega, cristata, ventricosa. 



Amphitrite. Tube elongated, cylindrical, 

 attenuated at base, membranaceous or coria- 

 ceous, generally naked exteriorly. 



A. ventilabrum, penicillus, magnifica, vesiculosa, voluta- 

 cornis, infundibulum. 



SERPULEA. 

 Tube solid and calcareous. 



Spirorbis. Tube testaceous, convoluted 

 into an orbicular, discoidal spire ; flattened 

 and fixed at base. 



S. nautiloides, spirillum, carinata, lamellosa, tricostale. 



Serpula. Tubes solid, calcareous, irregu- 

 larly convoluted, grouped or solitary, attached 

 to marine bodies ; aperture terminal, rounded, 

 very simple. 



S. vermicularis, fascicularis, intestinum, contortuplicata, 

 plicaria, glomerata, decussata, protensa, infundibulum, annu- 

 lata,cereolus, filograna, vermicella, filaria, pellucida, minima, 

 echinata, sulcata, costalis, dentifera, sipho, arenaria. 



Vermilia. Tube testaceous, cylindrical, in- 

 sensibly tapering posteriorly, more or less con- 

 torted, fixed by the side to marine bodies ; 

 aperture rounded, margin often armed with 

 one, two, or three teeth. 



V. rostrata, triquetra, bicarinata, eruca, subcrenata, plici* 

 fera, scabra, tœniata. 



