CONCHYLIA— D/THYi?^. 2. 18 



2. TEREDO— L/AWE. 



Testa orbicularis, hemisphcerica, asquivalvis, tubo longo cylindraceo cum 

 accessoriis varus postici terminata. Cardo dente longo curvo sub mar- 

 ginem inserto, in utrdque valvd : later alibus nullis. Ligamentum 

 nullum. 



Shell orbicular, hemispherical, equivalve, terminating behind in a 

 long cylindrical tube with its various appendages. Hinge with a 

 long curved tooth in each valve, inserted under the margin : 

 lateral teeth none. Ligament none. 



Besides the long cylindrical tube, which is gradually formed for 

 protection in the passage of the animal through the wood, the valves 

 of this genus may be distinguished from those of the Pholas by the 

 triangular projection at the anterior end of each. They are all 

 inhabitants of the ocean, ministers of the decomposition and 

 destruction of timber, the calamity of ships and driven piles. 



Linne, and the subsequent writers on systematic concholoo-y, 

 have formed the characters of this genus from the cylindrical tube. 

 Lamarck has made his specific characters from the differences of the 

 appendages placed near the smaller end of the tube. In conformity, 

 however, with the other bivalves, we consider the primary valves as 

 offering the most decided and natural basis of specific distinction. 



Lamarck has also placed this genus and that of the Pholas in his 

 division with the ligament external. They have, however, no per- 

 manent ligament, as we observed of the Pholas tribe, but the 

 valves are merely connected together by a fold of the animal 



