XJNIVALVES.-^TEREDO. 



149 



Glomerata. Denticulata. 

 Lunibricalis {Cork-screw S.) INIelitensis. 



Polythalamia. Norvvegica. 



Arenaria. Porrecta. 



Anguina (Serpent.) Vitrea. 



*Vermicularis. Cancellata. 



Aquaria (Watering-pot.) Stellaris 



Echinata. Gigantea. 



Ocrea (Boot.) Citierea. 



Protensa. * Sulcata. 



Decussata. *Ovalis. 



Proboscidea. *Reflexa. 



Afra. * Cornea, 



Cereolus. *Bicornis. 

 Cornucopi8e(i/orn of Plenty.) *Perforata. 



Goreensis. *Lactea. 



Intestiiialis. *Lagena. 



Infundibulum, *Retorta. 



Pyramidalis. *Incurvata. 



TEREDO.— Ship-Worm. 



Animal — a Terehella, with two calcareous hemispherical 

 valves cut off before^ and two lanceolate ones: Shell 

 tapering f fiexuouSy and capable of penetrating wood. 



There are but three species of this genus : the first is the 

 Teredo navalis, or common ship-worm, it is very thin, 

 cyhiidrical, and smooth, and is more or less twisted, ra- 



