THE ECONOMIC MOLLUSCA OF ACADIA. Ill' 



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- 



