354 INVERTEBRATA OF MASSACHUSETTS. 



they now exist in such myriads, is enough to satisfy the devout mind 

 that they have still some indispensable office to perform. The great 

 purpose of their existence seems to be, in the first place, to remove 

 dead and decaying substances, before they become obnoxious. Their 

 multitude and minuteness enables them to do this silently, promptly, 

 and effectually, quite unperceived. In the next place, they are em- 

 ployed for food by the higher animals, until they become directly 

 useful to man by nourishing the food on which he himself subsists. 



But it is not my design to generalize. This might satisfy the un- 

 derstanding, but not the cupidity of man. Let us therefore proceed to 

 particulars. 



Of all the animals in the preceding catalogue, there is but a single 

 one which interferes materially with the interests or possessions of 

 man. It is a little animal which infests and destroys timber and 

 wooden structures built in salt water. It has been named Limnoria 

 terebrans. 



The LIMNO^RIA TE'REBRANS is a minute crustaceous animal about 

 three twentieths of an inch long, and not quite 

 half as broad. Its two ends are rounded, and its 

 sides parallel, so as to have nearly the shape 

 of a small maggot. Its color is grayish. The 

 body is composed of fourteen segments, the 

 seven which succeed the head each bearing a 

 pair of short legs. It is capable of both swim- 

 ming and crawling. When touched, it rolls it- 

 self up, by bending down the head and tail. Its 

 food, contrary to the general, if not otherwise 

 universal rule, among Crustacea, is vegetable. 

 This little animal was first detected by Robert Stevenson, Esq., the 

 architect of the Bell Rock Light-house, in 1808. He sent it to Dr. 

 Leach, who gave it its name and described it, in 1811. Its habits and 

 ravages have since been fully described by Dr. Coldstream and Mr. 

 Thompson, in the " Edinburgh New Philosophical Journal," and my 

 own observations have added but little to what may be gathered from 

 theirs. 



The animal attacks, by preference, soft wood, and the softest parts 

 of wood. It selects pine, if it can be had ; but it was observed at Bell 

 Rock, that oak, birch, and all other wood there exposed, except teak, 

 was more or less perforated. All wooden structures immersed in the 

 sea are liable to its attacks. Sea-bulwarks are undermined, the piles 



