Fossil Bones and Pseudo-Coprolites of the Crag. 97 



weighed between 600 and 700 grains each ; their external sur- 

 faces were much water-worn and highly polished. They were 

 brownish-ferruginous in colour, easily fractured, and, when tritu- 

 rated in an agate mortar, yielded a yellowish-red powder. 

 Density, at 60° F., 2-815 or 2-850. 



Composition per cent. : — 



Water, with a little organic matter . 



4-000 



3-560 



Salts soluble in'water (chloride of sodium and 





sulphate of soda) . . . . 



. traces. 



traces. 



Silicic acid, coloured red by a little unde- 





composed silicate of iron 



. 5-792 



6-309 



Carbonate of lime . . . . 



. 10-280 



8-959 



Carbonate of magnesia 



. a trace. 



a trace. 



Sulphate of lime . , . . 



distinct traces. 



0-6]l 



Phosphate of lime (tribasic) 



. 70-920 



69-099 



Phosphate of magnesia 



traces onlv. 



traces. 



Perphosphate of iron 



. 6-850 



8-616 



Phosphate of alumina 



. 1-550 



2-026 



Oxide of manganese 



, traces. 



0-016 



Fluoride of calcium . . . . 



. 0-608 



0-804 



100- 100- 



Nitrogen, per cent. ..... 0-0254 undetermined 



/3. This specimen was brought from the same part of the coast 

 as the preceding, but differed from them in possessing a more 

 irregular form, and in exhibiting imperfect evidences of a bony (?) 

 structure. 



It was found impossible to determine its specific gravity, in 

 consequence of the presence of numerous air-cavities. 



Analysis showed it to possess the subjacent per-centage com- 

 position : — • 



Water, driven off at from 300° to 350^ F. . . 2-600 

 Water and organic matters expelled at a red heat 9*000 

 Chloride of sodium, &c. .... evident traces. 



Carbonate of lime 

 Carbonate of magnesia 

 Sulphate of lime 

 Phosphate of lime 

 Phosphate of magnesia 

 Perphosphate of iron , 

 Phosphate of alumina 

 Peroxide of iron 

 Alumina . 



Fluoride of calcium . 

 Silicic acid 



The proportion of nitrogen was not estimated. 



VOL. XII. 



. 39-500 

 . 0-5-20 

 distinct traces. 

 15-860 

 traces. 

 9-200 

 4-708 

 none. 

 6-212 

 1-698 

 10-601 



99-899 

 H 



