29 APRIL 1905, Page 30


I.TO THE EDITOR OP THE " SPEOTATOW] SIE,—Referring to the interesting article on "Destructive Life" in the Spectator of April 22nd, I beg to mention an illustration which exists in this neighbourhood. The great blocks of limestone on the Plymouth Breakwater are often honeycombed and destroyed by what might seem a very feeble agent. A little bivalve makes holes in the stone, it is supposed by secreting a strongly acid fluid. These holes increase in size with the growth of the creature, and so gradually destroy the blocks, which have to be renewed at considerable expense. When the British Association met here in 1877 I was able to submit some living specimens of these mischievous little workers.—I am, Sir, &c., Wychbury, Mannarnead, Plymouth. • BzwvirELL MILD.