176 LIFE ON THE EARTH. 



ward, who consumed the latter part of the seventeenth 

 century in wrangling about l formed stones/ ' plastic 

 forces,' and 'lusus natune.' 



The learned Dr Robert Plot, the first Keeper of 

 the Ashmolean Museum in Oxford, in that valuable 

 Natural History of Oxfordshire (1677), which was 

 the model for many goodly volumes in other counties 

 of England, after carefully describing many Ophio- 

 morphites, Ostracites, Belemnites, and Cockles lying 

 in their stony sepulchres, is brought to consider the 

 great question then so much controverted in the 

 world. 



1 Whether the stones we find in the form of shell- 

 fish, be lapides sui generis, naturally produced by 

 some extraordinary plastic virtue latent in the earth 

 or quarries where they are to be found? Or whether 

 they rather owe their form and figuration to the shells 

 of the fishes they represent, brought to the places 

 where they are now found by a deluge, earthquake, 

 or some other such means, and there being filled 

 with mud, clay, and petrifying juices, have in tract 

 of time been turned into stones, as we now find 

 them, still retaining the same shape on the whole, 

 with the same lineations, sutures, eminences, cavities, 

 orifices, points, that they had whilst they were shells. 



'In the handling whereof (he tells us), 'though 

 I intend not any peremptory decision, but a friendly 





