THE STOEY OF .FISH LIFE. 

 CHAPTEE I. 



INTRODUCTION. 



The Story of Fish Life began ages and ages ago. 

 Of this we are assured, not by any written record, 

 but through the labours of those who spend their 

 lives in exploring the dried basins of ancient lakes 

 and seas, searching for the dead which may in- 

 cidentally have been preserved therein. The 

 accumulated results of these explorations have 

 provided us with a rich material for study in 

 the shape of the hard parts, at least, of fishes 

 of many kinds, the like of which, in many cases, 

 we shall never see again. But some of these may 

 be traced through a long series of geological forma- 

 tions, up to their living descendants ; and serve to 

 fill gaps otherwise incomprehensible. They enable 

 us to weave out of the whole of the collected 

 evidence a story, as plainly as though we had 

 transcribed it from the more familiar print. 



But our story is even now by no means a con- 

 nected story : there are many gaps which we can 

 never hope to fill. For instance, the earliest of 

 the known fishes was most certainly preceded by 



