est YG). pe 
the same geological formation in the North of Ireland. These 
paramoudras are more frequently hollow than the ordinary 
nodular flints though they do not uniformly contain the fine 
powdery material which was present in the specimen I met 
with, but occasionally, as noted by Sir Charles Lyell, they 
have an internal cylindrical nucleus of pure chalk much harder 
than the ordinary surrounding chalk and not crumbling to 
pieces like it when exposed to the winters frost. In com- 
mon with the other chalk flints of this district the exterior 
surface of the paramoudras is white and rough, while the 
interior is of a dark tint. 
The particular specimen which yielded me the fossiliferous 
powder was about a foot in diameter and more spheroidal than 
the generality of the potstones. The manner in which the 
interior cavity became inclosed may be understood by supposing 
that the process of the deposition of the silica, by which 
the ordinary cup-shaped paramoudras were formed, was con- 
tinued further, until the cup was arched over with a solid 
layer of flint, and thus the soft incoherent ooze included within 
was preserved safely from the effects of all further mechanical 
influence. _ Without entering here into the vexed question 
about the formation of the flints in the chalk, it may be as 
well to notice that the beautifully perfect state of preservation 
of the various delicate fossil organisms in the interior of this 
flint, when compared with the nearly complete obliteration of 
their structures in the enveloping chalk points to the conclusion, 
that the period in which the flints were formed must have been 
previous to that consolidation of the mass of the chalk by which 
the smaller fossils were mostly destroyed. The flint powder 
or flint meal which was preserved in the cavity of this flint, 
like the ashes of the dead in a funereal urn, had the appear- 
ance of a very fine flour of a creamy yellow tint, thus differing 
but slightly from the soft earthy white chalk in which the 
flints are here imbedded. The /imest portions of the flint- 
meal, under high powers of the microscope were seen to be 
