172 TEREDINID^. 



close together, slight, and scarcely raised, but existing in all 

 perfect specimens ; siphonal or longitudinal ridge perceptible 

 only in the young ; aperture obliquely truncated in front, and 

 sometimes also at the back, making that part similar to the 

 slit end of a Dentalium. Valves, L. 0-3, B. 0-3 ; pallets, 

 L. 0-2, B. 0-1 : sheath, L. 6-0, B. 0-3. 



Var. occlasa. Shell like the analogous variety of T. Nor- 

 vegica. 



Habitat : (both the typical form and variety) in fir 

 wood or deal, composing the harbour piles at Sheerness 

 (Sir Everard Home), Heme Bay (Hanley), Yarmouth 

 pier or jetty (Rev. H. R. NeviU), Ramsgate pier 

 (Rev. Sir Charles Macgregor, Bart.); in elm stakes used 

 by fishermen for fastening theii' nets at Broadstairs 

 (Metcalfe); boats left long at anchor, and shipping- 

 stages in the lower reaches of the Thames and Medway 

 (Baxter) . It swarms along the European coasts from 

 Christiania (Asbjornsen) to Sicily (Delle Chiaje and 

 Philippi), as well as in the Black Sea (Pallas and Hein- 

 rich) and Oran in Algeria (coll. Deshayes); with T. 

 Norvegica in the boughs of trees, placed in Kiel bay to 

 collect the fry of the common mussel (Meyer) ; " Hell- 

 gate, New York, in a British frigate sunk during the 

 revolutionary war ^' (Try on) . 



This is the Dutchman's pest ; and he does not seem 

 to be troubled with any other kind, at least of the mol- 

 lusk tribe. It is extraordinary that the animal of such 

 a common species has never been described by any 

 author, except in a general way by Home and Vrolik. 

 Mr. Hanley procured some remarkably fine sheaths 

 from the pier at Heme Bay (supposed by him to belong 

 to T. megotara), which measure upwards of a foot in 

 length : for a couple of them I am indebted to his kind- 

 ness. They are much more solid than those taken from 



