On the Structure of the Limnoria Terebrans. 317 



in holes in wood, which it forms for itself by burrowing. As it 

 is gregarious, and very abundant in situations favourable for the 

 exercise of its habits, it soon produces great effects on the wood 

 to which it attaches itself. By boring in all directions, it so dis- 

 integrates it, as to allow the sea to wash away its surface : and 

 thus, layer after layer of the wood is first riddled by the borer, 

 and then abraded by the sea, until the whole piece of timber at- 

 tacked is completely destroyed. 



The ravages of the limnoria were first particularly observed 

 by our distinguished civil-engineer, Mr Stevenson, who, while 

 engaged in the erection of the Bell-Rock Lighthouse, noticed 

 that the beams of wood, used in some of the temporary works, 

 were destroyed by its borings in a very rapid manner. He sent 

 specimens of the animal, contained in the wood which it had 

 bored, to Dr Leach, who determined it to possess characters 

 sufficient to entitle it to be considered as t?he type of a new 

 genus, to which he assigned the name of Limnoria, placing it 

 in the family Asseiides, of the order Myriapoda, in his new ar- 

 rangement of the Crustacea. In a systematic enumeration of the 

 same class of animals, afterwards published by Dr Leach, he placed 

 the Limnoria in the order Isopoda, — subclass Edriophthalmia, — 

 of the class Malacostraca, which is characterised by sessile eyes, 

 palpigerous mandibles, and the want of appendages to the legs. 

 The genera grouped in this arrangement along with the Lim- 

 noria are Eurydice and Cymothoa. Latreille and Lamarck 

 make the Limnoria only a species of the last named genus. It 

 is chiefly composed of animals, which are the parasites of whales 

 and fishes, sucking their blood, and differing in other respects 

 so much from the Limnoria, although they resemble it in gene- 

 ral structure, as to justify their being dissociated from it. 



Since it was first observed at the Bell-Rock, the Limnoria 

 has been found on many parts of the coasts of Britain, and has, 

 in some places, been the cause of most serious injury to piles of 

 wood supporting various useful erections on the shores of the 

 sea. However, notwithstanding the extent and importance of 

 its ravages, the animal has not yet met with that attention from 

 naturalists which has been bestowed on other agents of destruc- 

 tion affecting the interests of man. Dr Leach announced it, in 



VOL. XVI. NO. XXXII. APRIL 1834. Y 



