110 
BULLETIN OF THE NATURAL HISTORY SOCIETY. 
The time of breeding of this species differs somewhat with the 
locality, but it takes place generally in the spring or summer months. 
They are very prolific. The young at first can swim freely about, but 
in a very short time (one writer says four days) they are fully equipped 
for their life work, and attaching themselves to wood, begin to bore 
their tunnels. After entering the wood, they increase rapidly in size, 
so that the adult burrows are many times larger than those by which 
the young enter. It is thought that as a rule they do not live longer 
than a year or eighteen months. They require pure salt water, free 
from sediment, and cannot generally live in brackish or polluted 
situations. Their tubes are sometimes ten inches long, but generally 
not more than half that length. 
A piece of Teredo-bored wood shows but little outward trace of the 
condition within. Except for the small holes made by the entering 
young, it may appear quite sound, when in reality riddled by the 
burrows and composed of almost nothing but their calcareous tubes. 
Along with the Teredo , there is frequently found a small crustacean, 
Limnoria lignorum, which also forms burrows and is very destructive. 
They work, however, in different ways, for the latter attack only the 
surface of the wood, and honey-combing it so thoroughly that nothing 
is left but partitions between burrows, allow it to be easily destroyed by 
the waves. As the outside is removed, they progress deeper, and so 
rapidly do they work that an inch a year is frequently removed all 
around the largest submerged timbers. The minute size of the burrows, 
about one-sixteenth of an inch in diameter, and the absence of a 
calcareous lining, as well as the presence of the crustacean itself, will 
always distinguish its ravages from those of the Teredo. It largely 
replaces the latter on those parts of the shores of Acadia where the 
Teredo does little harm, i. e., on the Atlantic Coast of Nova Scotia and 
around the Bay of Fundy, and it does great damage in these localities. 
It is particularly destructive at Dierby. The Teredo , on the other hand> 
perforates the wood through and through, and makes it so fragile that 
it will break under a slight shock. It seems to have little preference in 
regard to the wood it attacks, the hardest and softest being equally 
injured. The southern palmetto is said to withstand it. 
Economics. About the years 1730-32, great damage was 
done to the dykes of Holland by this Teredo. A general sub- 
mergance of the country was threatened, and the consequent 
alarm led to the careful study of the habits and structure of 
*the animal. Since then, it has appeared in numbers at 
different periods. In 1858 fresh alarm was caused, which 
resulted in the appointment of a commission to investigate 
vthe whole subject and experiment upon different methods for 
