THE ECONOMIC MOLLUSCA OF ACADIA. 
lire 
withstanding its ravages. An account of the work of the com- 
mission, by one of its members, is given in the first of the 
papers whose titles are below. 
The animals work with extreme rapidity. In San Fran- 
cisco Bay, they have destroyed great timbers within eighteen 
months, and even in certain cases within six months. It is 
recorded also that in Chesapeake Bay they have perforated 
small timbers completely in six weeks. Ships have been 
riddled on their first voyages, It is impossible to calculate 
the enormous damage annually done by this and allied species 
to naval works in different parts of the world. 
In our own waters much damage has been done at Pictou 
and other places on the North Shore; piles of wharves and 
bottoms of ships alike suffer. Mr. Murphy, in his admirable 
paper quoted below, says that at Sidney Harbor, Cape Breton ? 
“ the Teredo is seemingly as destructive, if not more so, than 
at any point on our coast.” Mr. Whiteaves, in one of his 
reports, tells us that “ Ship-worms of large size are said to be 
found at Halifax.” 
On the southern coast, their work is likely to be confounded 
with that of Limnoria lignorum, referred to above. It was 
probably the work of both together that completely destroyed 
within a period of six years a large and strong tide-dam at 
Frye’s Island, Charlotte County, but it is the Limnoria , as 
Prof. Verrill points out, that does the damage to weir-posts 
in that region. In St. John harbor they do no damage. Mr. 
S. W. Kain tells the writer that piers do not need protection 
from Teredo , though Limnoria is somewhat injurious. Pieces 
of timber which have been under water for many years show 
no trace of the presence of the former, and ships which enter 
the harbor infested by them, are free from them within two 
days. It is generally believed that this is caused by the great 
amount of fresh water in the harbor. Mr. Kain says : 
“ There seems to be a consensus of opinion among all shipping 
men that the Teredo is not found in the Harbor of St. John, 
nor in any harbor where there is any considerable body of 
fresh water.” The cause assigned no doubt explains the kill- 
ing of those which are brought into and their absence from the 
