ZOOLOGY. 265 



35. Teredo. Ship-Worm, or Piercer. Inhabitant a Terre- 

 bellciy or Ascida. 



Shell tubular, tapering, slender, curved, one extremity closed 

 by two hemispherical, and the other, by two lanceolate 

 valves. Plate 5, fig. 35. 



Though this genus is described as possessing valves, they 

 are not of the nature of those of the Multivalve genera, the 

 valves being rather parts of the animal than of the shell ; this 

 genus is extremely injurious to shipping, as they readily 

 penetrate the hardest oak, as likewise posts or piles, that are 

 emersed in water ; they are confined io the ocean. 



3Q. Sabella. Concrete-Shell. Inhabitant various, as 

 Neriesy Amphitrite, Sfc. 



Shell or case tubular, composed of particles of sand, broken 

 shells, and calcareous matter, cemented, by a glutinous 

 exudation. Plate 5, fig. 36. 



It is not at present determined by (he most able concho- 

 logists, whether this genus has a claim to its present situation 

 among Testaceous shells, but as no beiter cr more natural 

 station has been assigned to them, we leave lliem as previ- 

 ously arranged. They are found in the sea, and also in fresh 

 Avater ditches, sometimes affixed to rocks and shells, and 

 at others, buried in the mud or sand. 



