38 NOTES ON THE NATURAL HISTORY OF THE BELL ROCK. 



longer necessary, while developing others more appropriate 

 to their new sphere of existence, till, like their big brother the 

 whale, from being a four-footed animal they became quite 

 fish like in appearance, even to the cultivation of a dorsal 

 fin, though still possessing rudimentary traces of their former 

 construction. Change is apparent on every hand in the plan 

 of nature ; ages were necessary for the evolution of our present 

 day horse from his five toed ancestors ; and after all it does 

 not seem so very startling when the transformation is enacted 

 before our very eyes in a few short stages, as in the case of 

 the common frog, from the gill breathing tadpole to the lung 

 breathing adult. More startling it is to learn that man 

 himself was at one time a gill breather, and, as biologists 

 affirm, still exhibits traces of gill clefts at one stage of his 

 embryonic development. 



