VOL. XLIV.] PHILOSOPHICAL TRANSACTIONS. 323 



ruff into the jar to it, which the bansticle immediately assaulted and put to flight, 

 having in the conflict torn oft' a good part of its tail , and would probably have 

 killed it, had he not separated them very soon. » 



The endeavours these pricklebacks use, and the ability they have, to get from 

 place to place, are extraordinary ; for though the largest of them scarcely measures 

 above 2 inches in length, he has seen some of them leap out of the water a foot 

 high perpendicularly, and even much farther in an oblique direction, when they 

 wanted to get over boards or stones, or some other obstacle to their passage. It 

 is scarcely to be conceived what damage these little fish do, and how greatly de- 

 trimental they are to the increase of all the fish in general among whom they in- 

 habit. For it is with the utmost industry, sagacity and greediness, that they seek 

 out and destroy the spawn of all sorts of fish ; and indeed all the young fiy, that 

 come in their way, are pursued by them with the utmost eagerness, and swal- 

 lowed down without distinction, provided they are not too large. In proof of 

 what is here asserted, the bansticle beforementioned in the glass jar, did, on the 

 4th of May, devour, in 5 hours time, 74 young dace, which were about a quarter 

 of an inch long, and the thickness of a horse-hair. Two days after it swallowed 

 62, and would doubtless have eaten as many every day, could he have procured 

 them for it. 



Nature has furnished this little fish with a kind of breast-plate or armour, to be 

 its defence against any outward injury : she has likewise bestowed on it several 

 offensive weapons or spines, placed on its sides and back, which it immediately 

 erects on the least appearance of danger, or when it attacks some other fish. The 

 sharpness of these prickles guards it well enough from larger animals, that might 

 otherwise prey upon it ; but neither these, nor all the endeavours it can use, are 

 able to free it fi-om an enemy that torments it even to death ; viz. a kind of louse, 

 of an oval figure, having eight legs, and a very transparent body, which is able 

 either to swim or crawl, and sticks on it so fast, sucking and plaguing it all the 

 while, that it makes it almost mad. One remarkable particular in this louse is, 

 that its little fibrillous fins are always in motion, whether the creature be swim- 

 ming about, or fixed on the fish. 



All fish regulate their times of eating and abstinence by the temperature of the 

 air, and the quarter fi-om whence the wind blows ; and would those persons who 

 are lovers of angling take the pains to keep a few small fish in glasses, they might 

 at any time easily foretel, from their taking or refusing food, what sport is to be 

 expected, and often save themselves many a weary step taken to no purpose. 



He always observed, among the fish he kept in jars, that such as have lived a 

 while together, contract so great an affection for each other, that if they are 

 separated they become melancholy and sullen, and are a long time before they 

 forget the loss. About Christmas he put 2 ruffs into a jar of water, where they 



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