SILVER FISH. 117 



which, when disturbed by light being thrown on them in any of their 

 very various kinds of resorts, dash out of sight again into some 

 concealed nook with a speed almost like the passing of a flash of 

 light. 



Though called " Silver Fish " from their bright silvery clothing of 

 minute scales, they are not in any way related to fishes, neither are 

 they insects. They belong to the division of Thysanura, which differ 

 from insects in not going through a regular metamorphosis (that is, 

 not through larval and pupal changes up to perfect development), and 

 also they never acquire wings. 



The Lepisma saccharina is about one-third of an inch in length, and 

 silvery white in colour. The head is furnished with tapering horns 

 about two-thirds of the length of the body, and the eyes are black ; 

 the mandibles (jaws) are strong and curved. The body, at the widest 

 part, is about twice the width of the head, or a little more, and is 

 thickest at the fore part, gradually tapering from the second segment 

 behind the head to the tail. 



Each of the three segments next to the head bears a pair of legs 

 furnished with two clawed feet ; at the tail extremity are three long 

 bristle-shaped appendages, one pointing backwards, the two others 

 pointing sideways at almost a right angle with the body. Propagation 

 is by eggs. 



The species was noted as long ago as 1665, in a small book 

 published by the Royal Society, as injurious to books and papers, 

 its general appearance being quaintly but not unaptly described 

 as: — "Its head appears big and blunt, and its body tapers from 

 it toward the tail, smaller and smaller, being shaped almost like a 

 ' carret.' " 



My own chief acquaintance with it was many years ago as in- 

 habiting one or more of some deep flour-bins, holding perhaps a sack 

 of flour apiece, in a dry warm room opening from the kitchen of a 

 large country house ; but as far as I remember, it rarely strayed 

 to other parts of the house. Its most favourite food, as recorded, is 

 starched clothing, linen, or curtains ; also it is mentioned as some- 

 times doing very serious damage to silks, with the remark added that 

 these " had probably been stiffened with sizing." 



The chief cause of its depredations appears to be the attraction 

 possessed by paste. It is mentioned that it is a serious pest "in 

 libraries, particularly to the binding of books, and will frequently eat 

 off the gold lettering to get at the paste beneath. . . . Heavily 

 glazed paper seems very attractive to this insect, and it has frequently 

 happened that the labels in museum collections have been disfigured 

 or destroyed by it, the glazed surface having been entirely eaten 

 off. ... Its damage in houses, in addition to its injury to books, 



