COPROLITE BEDS. 255 



of serpents. The latter substance, which is very like plaster 

 of Paris, was, and maybe still is, bought up at the rate of 

 nine shillings a pound from the Zoological Society by a 

 " doctor," or, perhaps, chemist. What he did with it was a 

 mystery to most people, but no doubt he made the pur- 

 purate of ammonia from it. 



The well-known fossils called " coprolites," consist 

 chiefly of phosphate of lime, and received their name 

 because they were supposed to be the fossilised droppings 

 of huge saurians, or lizards, and other animals ; but though 

 some are no doubt true coprolites, and all evidently result 

 from the decay of animal matter, they have generally lost all 

 trace of organic origin, and are simply nodules of bone- 

 earth, which when ground, or otherwise prepared, make a 

 valuable manure. They are found in large quantities in the 

 Suffolk Crag along with the bones and teeth of whales, &c., 

 and are washed up in such abundance on the beach that 

 people are constantly engaged in collecting them. 



The beds vary from a few inches to several feet in thick- 

 ness, and are found in Norway, the West Indies, Spain, and 

 South Carolina, but were first dug in Cambridgeshire, 

 where Dr. Henslow at once pronounced them to be " bone- 

 earth, which," he said, " we are at our wits' end to get for 

 our grain and pulse, and are importing as expensive bones 

 from Buenos Ayres." 



All animal matter contains a large proportion of carbon ; 

 and, as has been already mentioned, it seems probable that 

 many deposits of rock-oil are derived from the remains of 

 fishes, mollusks, Crustacea, and the other minuter forms of 

 animal life, of which many shales, limestones, &c., are 



