232 
lance from the valves the tube is of a firm, shelly texture', 
smooth and shining. The animal seems to have been ca- 
pable of separating itself from this tube, which is not 
attached to any sensible part of it, and of returning towards 
the place where it first entered ; in this case it forms a sep- 
tum behind it across the tube, contracting its dwelling to a 
size experience has taught it is sufficient. 
The Teredo navalis may be distinguished by the follow- 
ing— 
Spec. Char. Valves transversely striated on the posterior 
side; anterior side smooth, with only a few lines of 
growth. 
The dreadful ravages committed upon timber by this 
destructive borer, seems to have commenced as soon as 
timber was immersed in sea-water, and long before ships 
were invented ; whence I have named the Fossil species, 
antenautce , and would retain Linne’s name for the com- 
mon recent one that, has been so formidable ever since the 
Europeans visited India. Whether it penetrates the wood 
for food or only for shelter, is doubtful ; if it work for 
shelter only, why does it penetrate to such a distance from 
the surface? and if it feeds upon the wood, would notits 
mouth first enter, instead of ifs boring with its posterior 
part? The position of its mouth and the analogy of other 
testaceous animals, rather show that it feeds upon such 
small niolusca as may chance to enter the narrow porch of 
its winding habitation, and be surprized by a gigantic 
enemy lurking in secret.* 
Delamarck must have had a very imperfect specimen, 
or he would not have hesitated to have placed this as a 
Teredo (for he has observed its resemblance to that Genus 
and to Pholas), instead of confounding it with several other 
boring shells, which (independent of a calcareous covering 
attached to their external surfaces, and which, in a few 
* The Pholas, &c. appear often to recede to a distance from the external 
parts of their holes. 
