TEREDO. 173 



honeycombed pieces of wood, and have almost the po- 

 lish of ivory. Sometimes the pallets are distorted, and 

 the stalks are now and then double. The stalk passes 

 through the pallet ; but the upper part of it is seldom 

 visible, being covered by an accretion of the less com- 

 pact substance which forms the plate or main body of 

 this appendage. 



It was first identified by Loven, and afterwards recog- 

 nized by Thompson and the authors of the ' British 

 Mollusca/ as the T. navalis of Linne. His description 

 was taken fi'om the sheath onh^, and is so vague that 

 it may fit any species. Hanley remarked, in his 

 ' Ipsa Linnaei Conchylia,^ as follows : " It is impossible 

 to determine, from the language of Linne, to what par- 

 ticular species of shipworm the very comprehensive 

 term navalis shoidd be restricted. Our author has not 

 indicated the possession of examples ; consequently his 

 cabinet aflbrds no assistance in the investigation." I 

 was inclined at one time to adopt the specific name 

 marina, given by Sellius, which is prior to navalis ; but 

 I now believe that the word " marina " was used by him 

 only as an epithet, in an opposite sense to " terrestris.''^ 

 Linne, in the first edition of his ^ Fauna Suecica,' de- 

 scribed the sheath as a Dentalium (in the index as Tei^edo 

 navis) ; and he adds that it is the T. navalis of Sellius, 

 and inhabits ships and submarine piles or stakes. In the 

 last edition of the ' Systema Natm-ae ^ the ' Famia Sue- 

 cica^ is quoted, and then Vallisnieri, Sellius, and Plancus. 

 The first and last of these authors intended T. Norvegica. 

 That species, as well as the present, still inhabits the 

 coasts of Sweden, as they probably did in Linnets time ; 

 and since the name Norvegica is free from any doubt, 

 and it is therefore advisable to retain it under the cir- 

 cumstances, there seems to be no alternative between 



