420 Rev. W. Buckland on the Paramoudra, and 



It is probable that in cases where the body perished rapidly, there 

 was not time for this process of gradual substitution, and that flinty 

 matter of nearly the same coarse quality with the outer crust, was 

 introduced hastily into the void spaces that were left unoccupied 

 by the rapid decay of the animal nucleus. This coarser process is 

 that which appears to have taken place in a vast plurality of instances, 

 amongst which we must reckon that of the Irish Paramoudra, 

 whose history has led us to the present discussion on chalk flints, 

 among which they attain a size unusually gigantic, and often a 

 weight of nearly two hundred pounds. 



With respect to the general history of flinty nodules in chalk, 

 whether insulated irregularly or disposed at certain distances in 

 horizontal lines, I must observe that they seem to have originated 

 from causes not dissimilar to those which have produced both no- 

 dules and horizontal beds of chert in the calcareous strata of many 

 other secondary formations ; e. g. in the freestone of Portland, in 

 the mountain lime of Mells in the Mendip hills, and in the oolitic 

 limestone near Pickering in Yorkshire, and near Poligny, on the 

 north-west edge of the Jura mountains ; at which latter place are 

 extensive strata of chert disposed altogether in small nodules re- 

 sembling chalk flints, as to their shape, size, and position, and 

 without any organic nuclei. The chief difference appears to be, that 

 in the case of the chalk formation, the nodular arrangement of 

 the siliceous strata very much predominates, and in the other cases 

 the siliceous strata, though occasionally nodular (as at Poligny), 

 yet most frequently are disposed in continuous or nearly continuous 

 flat masses ; though even these sometimes pass into imperfectly 

 lenticular and tuberous concretions. The existence of insulated 

 siliceous concretions irregularly disseminated through limestone, is 

 common to almost all calcareous strata in which there is any ad- 



