388 Proceedings of' the Royal Society of Edinburgh. 



supposed to approach in character to the Lepisosteus, or Lepidosteus 

 of Agas^^iz. The scales were about three-fourths of an inch long by 

 somewhat less in breadth, and possessed a line lustre, and the usual 

 delicately punctured surface. They were found to contain — 

 Phosphate of Lime, with a little Fluoride of Calcium, 50.94 



Carbonate of Lime, 11.91 



SiUceous matter, 33.10) „„,„ 



Water, 3.48 P"'^" 



Potash and Soda, 47 



Bituminous matter, . . . . . . .12 



Phosphate of Magnesia, .... trace 



Animal matter, trace 



100.02 

 It is remarkable that the composition of these scales is very analo- 

 gous to that of the scales of the recent Lepisosteus, if we sup])ose the 

 perishable animal matter in the latter to be replaced by infiltration by 

 the hydrated siliceous matter in the fossil scales. In those of the re- 

 pent Lepisosteus, Chevreul found — 



Phosphate of Lime, .... 46.20 



100 



The result of the analysis of the bony rays of the Gyracanthus 

 may also be compared with the constitution of certain recent fish 

 bones. Those of the pike, as determined by Dumenil, consist of— r 

 Phosphate of Lime, .... 55.26 



Carbonate of Lime, * . . . . 6. 1 6 



Animal matter, 37.36 



Traces of Soda and loss, . . . 1.32 



100. 



If we suppose the animal matter to be replaced partly by siliceous 

 matter and partly by carbonate of lime, the composition of the recent 

 and of the fossil bones Ijecomes very similar. 



The ratio of the phosphate of lime to the carbonate of lime in the 

 Coprolites, according to the analysis formerly communicated to the 

 Society, does not differ much from the proportions in the above ana- 

 lysis of recent fish bones. The Coprolites may therefore be viewed 

 as aggregated masses of fish-bone earth, the animal matter having 

 decayed almost without any substitution, from fecal matter not pos- 

 sessing that structure and solidity which seem usually essential to 

 the proper process of mineralization by infiltration. Since his for- 

 mer communication, the author has found a trace of fluoride of cal- 

 cium in the Coprolites. 



It is remarkable, that the limestone matrix itself contains a very 

 decided trace of animal matter, doubtless derived from the great 

 quantity of animal remains which have been entombed in it. 



