58 Analysis of the Coprolites of Birds. 



&c., the general result of which I have alluded to above. He 

 proved that the solid excrement examined hy Dr. Prout, was the 

 urinary excretion only. The researches of WoUaston and Coin- 

 det have shown the closest relation between this and the drop- 

 pings of carnivorous birds ; while the analysis of hen's dung by 

 Vauquelin, and the recent numerous analyses of guano, show too 

 what might be expected to be the composition of the fecal mat- 

 ter of omnivorous birds, and the state to which it is reduced by 

 time, as has been guano. Let us tabulate these analyses, to see 

 at a glance their results. 



Earthy phosphate, 

 Uric acid. Ammonia, alkaline phosphate, Alk. salts. Org. mat. 

 and carb. lime. 

 Urine of lizards, several )n/i. o. o 'jo l. 



species, by Schreibers, \^^ ^ 3-33 phos. hme. 



Boa constrictor, (Prout,) 90-16 I'TO •SO^P'Tv"'^ B'lO* 2.94 



' ^ '-^ I carb. lime. 



Davy gives us no proportional results ; but he states the gen- 

 eral fact, that the urine of all the reptiles he examined, is nearly 

 allied to that of the boa constrictor in some cases, and in the 

 alligator is mixed with a large portion of phosphate and carbon- 

 ate of lime. Wollaston states that the excrement of the pelican 

 is like that of the boa. 



Carnivorous birds, (Coindet.) 



American sea eagle, 



" hunting eagle, 



" duke of Virginia, 

 Senegal eagle, 



One is impressed at once with the difference between these 

 droppings; those of reptiles being nearly pure uric acid, and 

 those of carnivorous birds pure urate of ammonia. If now we 

 suppose the urine of lizards to be placed in a state most favora- 

 ble for the complete decomposition of its uric acid, we should 

 have that element removed. There will remain urate of am- 

 monia and phosphate of lime — a compound wholly unlike your 

 coprolite. If we suppose that by time and exposure the urine 

 of the boa loses its urates, then we have left, phosphates, sul- 

 phates, chlorides, and a trace of carbonate of lime, substances 

 found in your coprolite also. But the proportions of these are 

 not only very different, but a large proportion of potash should 



* Potash and traces of common salt, 3'45. 



