36 



TEREDINA 



A fossil genus; consisting of a testaceous cylindrical 

 sheath, the posterior extremity closed, and exhibit- 

 ing* the two valves of the shell it incloses; the anterior 

 end open. 



. ^ ^ 



TEREDO. 



TEREDO NAVALIS. LifinCBus. 



This also, like others allied to it, is a testaceous scab- 

 bard or sheath, covering the animal, but not connect- 

 ed with its shell, and which ceases to exist in the Pho- 

 lades. The sheath is open at both ends, and the shell 

 it contains, being no longer fixed and adhering, closes 

 the posterior extremity. The internal shell consists 

 of two concave valves, each provided with a subulate 

 piece within, at the back of which the marks of the 

 two valves described in the second species are very- 

 visible. At the interior orifice of the sheath, the ani- 

 mal presents two small tubes, similar to the genus Sep- 

 taria. They commit great havoc by destroying the 

 planks of ships, piles of embankments, &c. 



La Marck makes no mention of the enormous spe- 

 cies so ably described by Sir Evcrard Home, and called 



