ARTIFICES OF ANIMALS, 235 



in a position entirely natural, upon the branches of trees or 

 bushes, so that they appear, at first sight, as if alive. It is a 

 common opinion where this bird is found, that it thus destroys 

 nine insects every day, and hence its name ; but as it is known 

 not to feed upon insects itself, but principally upon small 

 quadrupeds and birds, the object of this expedient is not per- 

 fectly obvious. Some have supposed that it was done merely 

 for amusement. The most probable explanation, however, is 

 that the insects are intended by this little hawk as a decoy 

 for the birds which it designs for its prey. This manoeuvre 

 is put in practice in the fall of the year, just before the severe 

 frosts begin, which by killing the insects deprive the smaller 

 birds of the food on which they have been accustomed to 

 subsist. They are of course, in the season of scarcity, led to 

 the bait their sagacious enemy has provided, and thus become 

 an easy prey.' 



Of the economy of the inhabitants of the water, as for- 

 merly remarked, our knowledge is extremely limited. But, 

 as the ocean exhibits a perpetual and general scene of attack 

 and defence, the arts of assault and of evasion must, of course, 

 be exceedingly various. For the preservation of some spe- 

 cies of fishes, nature has armed them* with strong and sharp 

 pikes. Others, as the perch kind, are defended with strong, 

 bony rays in their fins. Others, as the univalve shell-fish, 

 retire into their shells upon the approach of danger. The 

 bivalves and multivalves, when attacked, instantly shut their 

 shells, which, in general, is a sufficient protection to them. 

 Some univalves, as the limpet kind, attach themselves so 

 firmly, by excluding the air, to rocks and stones, that, unless 

 quickly surprised, no force inferior to that of breaking the 

 shell can remove them. The flying-fish, when pursued, darts 

 out of the water, and takes refuge in the air, in which it is 

 for some time supported by the operation of its large and 

 pliable fins. The torpedo is furnished with a remarkable 

 apparatus for self-preservation. It repels every hostile at- 

 tempt by an electrical stroke, which confounds and intimi- 

 dates its enemies. Several fishes, and particularly the salmon 

 kind, when about to generate, leave the ocean, ascend the 

 rivers, deposit their eggs in the sand, and, after making a 

 proper nidus for their future progeny, return to the ocean 

 from whence they came. Others, as the herring kind, though 

 * they seldom go up rivers, assemble in myriads from all quar- 

 ters, and approach the shores, or ascend arms of the sea, for 

 the purpose of continuing the species, and cherishing their 



