DESTROYERS OF SUBMERGED WOOD — MURPHY. 217 



composed of two or more segments. Limnoria is said also to 

 occur in the Pacific Ocean, and from its habits might be expected 

 to have a wide distribution. 



In my paper on the ravages of the Teredo Navalis and 

 Limnoria Liynoruin in Nova Scotia, on piles and submerged 

 timber, (see pp. 357-376, vol. V, Trans. N. S. Institute of Natural 

 Science, 1881-2), I brought this subject more prominently before 

 you. My remarks this evening are intended to supplement that 

 paper with such information as I have since obtained respecting 

 this insignificant in appearance, j^et destructive little isopod. 

 For here in Halifax Harbour where they are so destructive as to 

 destroy the piling of our wharves, or at least most of them, in a 

 period of eight or ten years, and have in seven years destroyed the 

 piles of the wooden railway bridge across the Narrows of our 

 harbor, involving an expenditure of many thousands of dollars, 

 there are not many questions of greater local importance to the 

 Engineer than that of devising some means whereby their 

 attacks may be arrested or prevented. The Limnoria has 

 also been charged with the grave oflfense of attacking the gutta 

 percha of submarine telegraph cables, with damaging tarred 

 ropes, used for mooring boats, and with the destruction of fisher- 

 men's weirs, as well as that of destroying all sorts of timber. 



We can only remedy these destructive operations by a precise 

 knowledge of the causes that produce them, such knowledge as 

 may enable us to check or at least to mitigate some of these un- 

 desirable consequences. 



In the Bay of Fundy where the water is clear, free from silt 

 and transparent, the Limnoria is active and very destructive. 

 Up the Bay where the tide during the ebb digs deep into the 

 muddy flats thus discoloring the water and making it mucid 

 there is no Limnoria. 



In the Annapolis Basin they are active : at the head of the 

 bay, where the water is muddy, they are not to be found. In 

 like manner in Halifax Harbor where the water is clear they 

 are active. At such places as are polluted by a discharge of sewer- 

 age into the harbor there are no Limnorise to be seen. We account 



