3 EVOLUTION OF LIFE. 



wonderfully extended ; in shape, they are like 

 a diamond, having, at least, one hundred sur^ 

 faces, by means of which, they are enabled to 

 take within their sphere of vision, a great num- 

 ber of objects. 



The optic nerves ofjish far surpass, in mag- 

 nitude and power, those of terrestrial animals ; 

 DR. MONRO, who has written professedly upon 

 the subject, says, that the weight of the eye of 

 a cod, and the depth of its axis, are equal to 

 those of an ox ; added to which, there is a sub- 

 stance called tipitum, placed at the bottom of 

 the eye, which, it is supposed, acts like a mir- 

 ror, in reflecting the luminous rays, so as to 

 enable the other parts of the organ of the eye 

 to condense them into a focus : by these means, 

 the concentration of the light to one point, is 

 so great, that fish can see, and distinguish dis- 

 tinctly, objects at night. They are destitute of 

 eyelids, in order that they may be constantly 

 on their guard, to avoid the attacks of other 

 predacious animals. 



The optic power of serpents, and of birds, in 

 general, and more especially of the predacious 

 order, is so well known, as scarcely to require 

 any detail. The following fact, will, however, 

 afford some idea of this wonderful power. MR. 

 BARBER, in the year 1778, being in company 

 with several gentlemen in Bengal, while on a 

 shooting party, killed a wild hog, which they 



