CONCHOLOGY. 27 



FAMILY III. 

 Amphitrit^a. Four Genera. 



1. Genus Pcctinaria, PI. V. 



Animal. Respiratory organs in general known, and disposed 

 at or near the anterior part of the body ; not separated or covered 

 by an operculum. 



Shell. A membranous or papyraceous tube in the form of a 

 reversed cone ; unfixed ; exterior covered with sandy adhesions. 

 Two species. 



Pectinaria belgica. Pectinaria capensis. 



2. Genus SabellaHa. PI. V. 

 Animal. But slightly differing from the Pectinaria. 



Shell. Composed of fragments and particles of marine substan- 

 ces, adhering to a tubular membrane ; some are detached, others 

 fixed; tubes cellular at the base; orifice expanded. Two species. 

 Sabellaria alveolata. Sabellaria crassissima. 



3. Genus Terebella. PI. V. 

 Animal. Body tubicular, elongated, cylindrically depressed, 

 attenuated posteriorly ; a row of nodulous and setiferous papillae on 

 each side; numerous filiform, twisted tentacula surrounding the 

 mouth. 



Shell. An elongated cylindrical and membranous tube, atten- 

 uated and pointed at the base; with sandy adhesions. Inhabits 

 the coast of New Holland. Four species. 



Terebella conchilega. Terebella cristata. 



T. ventricosa. T. vermicuta. 



4. Genus Amphitrite. PI. V. 

 Animal. Body tubicular, elongated, cylindrical, attenuated 

 behind with many annulated segments. 



Shell. An elongated cylindrical tube growing thinner towards 

 the base, of a tough membranous texture, and generally without 

 adhesions. Mediterranean sea. Seven species. 



Amphitrite ventilabra. Amphitrite vesiculosa. 



