210 Dr Hibbert on the Limestone of Burdiehouse, 



burgh, has had his views directed to this subject, as, indeed, to 

 other comparative inquiries of the same nature, relative to the 

 change which animal remains of so early a geological date as 

 those of Burdiehouse have experienced. His valuable memoir 

 on this subject will appear in the present volume of the Transac- 

 tions of the Royal Society of Edinburgh. 



I have been favoured by Mr Connell with the result of 

 his examination of the scales of the Megalichthys, which he has 

 subsequently compared with an analysis given by Chevreul of 

 the scales of the recent Lepidosteus. These two results, with 

 the view of comparison, I have arranged in a tabular form. 



M. Chevreul's Analysis of the Scales of 

 the recent Lepidosteus. 



Analysis of the Scales of the Fossil 

 Megalichthys, by A. Connell, Esq. 



Phosphate of Lime, with a little 



Phosphate of Lime, . . 



. 46.20 



Fluoride of Calcium, 



. . 50.94 



Carbonate of Lime, . . . 



. 10. 



Carbonate of Lime, . . 



. . 11.91 



Phosphate of Magnesia, 

 Carbonate of Soda, . . . 



. 2.02 

 .10 



Phosphate of Magnesia, 

 Potash and Soda, . . 



trace 

 . . .47 



Gelatinous Animal Matter, 



. 41.10 



Animal Matter, trace 





Fatty Matter, 



40 



Siliceous Matter, . . 



33.10 







Bituminous Matter, . . 



3,48 



36.58 



. . .12 



99.82 



100.02 



Upon the assumption that the scales of the recent Lepidos- 

 teus and those of the Megalichthys identify themselves with each 

 other, as far as external character and consistence are concerned, 

 the foregoing Table of chemical comparison is a most important 

 and instructive one. 



With regard to the earthy ingredients of the phosphate of 

 lime and carbonate of lime, it will be seen at first view, that, in 

 both the fossil and recent animals, they constitute about three- 

 fifths of the solid matter of the scales. In the fossil animal, they 

 have remained in a proportion, most probably, unalterable. 



