108 HUGH MILLER'S MODIFICA TIONS. CHAP. ix. 



edition, published in 1846, Mr. Miller says that he had 

 found it necessary to make a good many additions tc 

 the volume, and several alterations in the text, where 

 the statements appeared to require modification. 



" I need here," he says, " refer to but one of those modi- 

 fications ; and this chiefly that I may have an opportu- 

 nity of acknowledging my obligations to the meritorious 

 individual through whose kindness I have been furnished 

 with the data on which it has been made. It was stated 

 in the two former editions that there is a gradual increase 

 of size observable in the progress of ichthyolitic life, 

 from the minute fish of the Silurian System up to the 

 enormous Holoptychius of the Coal Measures, the largest 

 of all the ganoids ; and that the Old Eed System, whose 

 lower beds border on the deposits of the Silurian fish, 

 and upper beds on those of the gigantic ganoid, ex- 

 hibited in its various formations this gradation of bulk, 

 beginning with an age of dwarfs, and ending with an 

 age of giants. 



" Since the appearance of the second edition, however, 

 it has been ascertained that there were giants among 

 the dwarfs. The remains of one of the largest fish 

 found anywhere in the system have been discovered in 

 its lowest formation near Thurso by Mr. Eobert Dick, 

 who, by devoting his leisure hours to the study of 

 geology, in a singularly rich locality, has been enabled 

 to add not a few interesting facts to those previously 

 accumulated truths of the science on which its sounder 

 theories can alone be erected, and who has kindly placed 

 at my disposal his collection of fossils. And the positive 



