THE SALVE BUG. 827 



along our shores, from Long Island Sound to Nova Scotia. In the Bay of Fundy it often does 

 great damage to the timbers and other wood-work used in constructing the brush fish-weirs, as 

 well as to the wharves, etc. At Wood's Holl it was found to be very destructive to the piles of 

 the wharves. The piles of the new government wharves have been protected by broad bauds of 

 tin-plate covering the zone which it chiefly affects. North of Cape Cod, where the tides are much 

 greater, this zone is broader, and this remedy is not so easily applied. It does great damage also 

 to ship timber floating in the docks, and great losses are sometimes caused in this w;iy. Com- 

 plaints of such ravages in the navy -yard at Portsmouth, New Hampshire, have been made, and 

 they also occur at the Charlestowu navy-yard and in the piles of the wharves at Boston. Probably 

 the wharves and other submerged wood-work in all our sea-ports, from New York northward, are 

 more or less injured by this creature, and, if it could be accurately estimated, the damage would 

 be found surprisingly great. 



" Unlike the Teredo, this creature is a vegetarian, and eats the wood which it excavates, so 

 that its boring operations provide it -with both food and shelter. The burrows are made by means 

 of its stout mandibles or jaws. It is capable of swimming quite rapidly, and can leap backward 

 suddenly by means of its tail. It can creep both forward and backward. Its legs are short and 

 better adapted for moving up and down in its burrow than elsewhere, and its body is rounded, 

 with parallel sides, and well adapted to its mode of life. When disturbed it will roll itself into a 

 ball. The female carries seven to nine eggs or young in the incubatory pouch at one time. 



" The destructive habits of this species were first brought prominently to notice in 1811, by 

 the celebrated Robert Stephensou, who found it rapidly destroying the wood-work at the Bell 

 Eock light-house, erected by him on the coast of Scotland. Since that time it has been investi- 

 gated and its ravages have been described by numerous European writers. It is very destructive 

 on the coasts of Great Britain, where it is known as the ' Gribble.' 



"The remedies used to check its ra/ages are chiefly copper or other metallic sheathing; 

 driving broad-headed iron nails, close together, into the part of the piles subject to their attacks ; 

 and applying coal-tar, creosote, or verdigris -paint, once a year or ofteuer." 



THE SALVE BUG MGA. PSORA, Kroyer. 



This is the largest species of Isopod living upon the New England coast, and attains a length 

 of two inches and a breadth of one inch. It occurs as a parasite on the cod and halibut. In addi- 

 tion to its large size, when adult, it may be readily distinguished by its large eyes, which nearly 

 cover the upper surface of the head, and approach closely together at their anterior extremities. 

 The first three pairs of legs are adapted for clinging to the surface of the fish on which it lives. 

 The body is oval, and broadest just in front of the middle. The Salve Bugs are used as an unguent 

 by the fishermen, who sometimes collect them in large quantities. 



230. THE ENTOMOSTRACANS. 



This order of crustaceans includes a vast number of small, generally minute, free-swimming 

 forms, frequently called water-fleas, whicli abound in both fresh and salt waters, and other and 

 generally larger species which occur as parasites on fish and other aquatic animals. The former 

 serve as an important article of food for many fishes, such as the menhaden and mackerel, while 

 the latter are frequently injurious to them, being often strangely modified, and burrowing deeply 

 into the flesh, from which they suck the juices, causing great irritation and at times perhaps 

 death. 



