4°4 



SPIN} 'FINNED GR O UP. 



are known as the three-spinecl (G. aculeatus), four-spined (G. spimilosus), andnine- 

 spined sticklebacks (G. pungitius) ; while in the United States G. novceboracensis 

 is the most familiar kind. The three-spined stickleback is a singularly variable 

 species, the plates which are present on the sides of the body in some specimens, 

 being wanting in others ; the unprotected condition being especially common in 

 the race from Central Europe. Very different in appearance from the others is 

 the fifteen-spined, or sea stickleback, in which the body is very long and thin ; 

 this species ranging as far north as Norway and the Baltic. It has recently been 

 ascertained that all the individuals of this stickleback die within a year of their 



GROUP OF STICKLEBACKS. 



Sea-stickleback (upper figure) ; Nine-spined stickleback (middle figure) ; and Three -spiued stickleback 



(lower figure), (nat. size). 



birth; so that we have here a second example of an annual vertebrate, the first 

 being the one mentioned on p. 389. 



Sticklebacks are extremely pugnacious, and at the same time highly voracious 

 fishes, the males engaging in fierce conflicts with one another ; while both sexes 

 consume a vast quantity of the fry of other fish, and are, therefore, most objec- 

 tionable denizens of preserved waters. It is not, indeed, that a single stickleback 

 can do a very great deal of harm, but the mischief results from the enormous 

 numbers of these little marauders. As an instance of this, we may once more 

 quote the well-known statement of Pennant, that a man employed by a Lincoln- 

 shire farmer to rid a stream of sticklebacks, for a considerable time made four 

 shillings a day by selling his catch at the rate of a halfpenny per bushel. In 



