300 DIMYARIA.—PHOLADID&. 
tion, about twenty inches long, the body of the 
animal has had no testaceous covering for the last 
three and a half inches; in two other. cells, of 
about two feet, no deposition appears for four and 
a half, and four inches and three quarters from 
their termination. All the timber at Portpatrick 
in which the Teredo had formed its habitation, is 
pine, and perhaps to this circumstance the supe- 
rior size of the animal may chiefly be attributed. 
Though it is well known that the Teredo bores in the 
direction of the grain, 1t may be observed that it 
does so whether the position of the wood be per- 
pendicular or otherwise. Captan Fayrer remarked, 
that it has a decided disposition to work horizon- 
tally. It is, however, often obliged to deviate 
from a straightforward course, to avoid such 
obstructions as nails, timber-knots, and tubes of 
its fellows, and make a winding or angular habi- 
tation according as such impediments occur ; but 
these circumstances seem not eventually to impede 
the progress of the animal, as some of the very 
largest specimens I have examined are the most 
tortuous. During the nine or ten years that the 
Teredo has been established at Portpatrick, it has 
not degenerated ; as specimens just received, which 
were alive in their native element a few days ago, 
are of equal size to those sent from the same place 
five years since, showing that it has not been 
affected by the cold of the winter season, as we 
might reasonably expect were the animals truly 
exotic. Ifthis animal had originally been intro- 
duced, and has been preserved only by occasional 
* importations, should we not rather look for it in 
those parts of the United Kingdom where vessels 
from every quarter of the globe are congregated, 
