ZOOLOGY. 



265 



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

 belluj or Ascida. - \ 



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

 by two iiemispjiencrJ, and the other, by two lanceolate 

 •valves, Plate 5, fig. 35. 



Though this genus is described as possessing valves, they 

 are not of tlie nature of those of the r>lull :"'^:^lve genera, the 

 valves being rather pnii; of the ar.iinal than of the shell ; this 

 genus is extremely injurio'is to shipping, as they readily 

 penetrate the hardest oak, as likew^i:e posts or piles, tnatare 

 emersed in water; taey are confined to the ocean* 



36. SabeUa. Concrete-Shell. Inhabllant various, as 

 Nericsy Amphitrite^ Sj'c. 



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

 shells, and calcareous matter, cemented by a glutinous 

 exudation. Plate 5, fig. 36. / 



It is not at present determined by the most able concho- 

 logists, whether (this genus has a chiim to its present sitGation 

 among Testaceous shells, but as no better or more izafiiral 

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

 ously arranged. They ar e found isi the sr^u, and also in fresh 

 water ditches, sometimes affixed to rocks and shells, iiwd 

 at others, buried in the mud or sa:id. 



