ACANTHOPTERYGII. 289 



eight years) in surprising quantities, and ascend in thick 

 columns the river Welland on which this town is situated. 



Their extreme multiplication is rather astonishing, for the 

 eggs of the stickle-backs are big, and they cannot lay many of 

 them. It is true, on the other hand, that they have but little 

 to dread from other fishes, seeing that they are defended 

 against them by sharp and strong spines ; but they have 

 internal and external enemies which unceasingly torment 

 them ; for instance, a species of binoculus, which attaches 

 itself to their skin, and sucks the blood; and the bothrioce- 

 phalus solidus, a species of the family of tcenia, which some- 

 times fills almost the whole abdomen, compressing their 

 intestines, and reducing them to a very small space. They 

 can subsist a tolerably long time out of the water, especially 

 when they fall into the humid grass. 



Bloch assures us that they live but three years, and his as- 

 sertion has not been controverted by facts. They are ex- 

 tremely agile fish, lively in their movements, and of an active 

 disposition. Henry Backer tells us that they leap vertically 

 out of the water, to more than the height of a foot, and that 

 in an oblique direction they can make springs still more con- 

 siderable, when they are obliged to pass above stones or other 

 obstacles. Their voracity is excessive. Backer has seen a 

 stickle-back devour in the course of five hours, seventy-four 

 new-born fish, of the species of the vandosia, each of which 

 was three lines in length. Accordingly no fish does more 

 injury to ponds than the stickle-backs ; and it is so much the 

 more annoying to see them introduce themselves there, as it 

 is extremely difficult to extirpate them. As aliment they are 

 but little esteemed. 



Theophrastus speaks of a little fish of Heraclea, on the 

 Lycus in Bithynia, which he names centriscus, and which 

 was absurdly numbered among those which spring spontane- 



VOL. X. U 



