^94 



of animals, which the world at large think of little value; 

 inasmuch as he will frequently have only a small portion, 

 nay, perhaps, only a scale of a fish, to work out his problem 

 by, yet it is by such an accurate knowledge of small things, 

 that results of the greatest interest may be come at. Who 

 would have believed, a few years ago, that we should be able 

 to declare with precision, the exact species of fish which 

 formed perhaps the principal food of the Ichthyosaurus, 

 from the undigested scales which are seen in the Coprolites 

 from Lyme Regis, or that have been sealed up for ages, 

 in the stony stomach of these monsters of a primeval world. 

 Yet this has been done, and from a single scale. (Vide "Z)r. 

 Buckland's Bridgewater Treatise^'' p. 191, to which work 

 I am indebted for much valuable information occurring in 

 this paper.) It is thus by attentively examining the peculiar 

 diagnostic characters which the scales of each family, genus, 

 or species of fish presents, that Agassiz has been enabled 

 to apply his classification of fishes, with so much efi'ect, to 

 Geological investigations, it being based upon the dermal 

 covering which appears the most durable. This partly 

 arises from the fact, that the enamelled condition of the 

 scales of most fishes, which existed during the earliest 

 Geological epochs, rendered them much less destructible 

 than their internal skeleton ; and cases frequently occur, 

 where the entire scales or figure of the fish are perfectly 

 preserved, whilst the bones within these scales have dis- 

 appeared altogether. Hence the perfect character of the 

 different families of fishes will be preserved for ages, 

 though not a vestige of their muscular or bony supports 

 remain. Thus are their very portraits indelibly stamped on 

 their rocky sepulchres. And it is of importance from 

 these medals of creation to notice, as Dr. Buckland 

 observes, " That all the great changes in the characters 

 of fossil fishes, have taken place simultaneously with the 



