6 HISTORY OF BRITISH ZOOPHYTES. 
zoophytes must have greatly abounded in the primitive seas, 
and that then, as now, their constant employment was to 
separate the carbonate of lime from the waters, thus forming 
a habitation for themselves, but at the same time uncon- 
sciously raising in the deep what was afterwards to be 
the residence of men, and what was to furnish materials for 
constructing the cottages of the poor and the palaces of the 
rich. Most certain it is that the mountain limestone, which 
abounds throughout our land, so useful in agriculture, in 
architecture, and in the manufacture of iron the most use ful 
of metals, was prepared at the bottom of the sea to answer 
all these important purposes. In breaking up the limestone 
found in our quarries there is abundant proof of its marine 
origin, for the organic remains, in general so plentifully 
found in it, are evidently those of molluscous creatures, and 
of zoophytes and other animals known to be denizens of the 
deep. Well do I remember the delight I experienced many 
years ago at finding in a little fertile field in my glebe at 
Stevenston, to which I had recently given a top-dressing of 
lime from Hullerhirst, in the same Ayrshire parish, the 
pretty entire remains of a Cassis, or helmet-shell, similar in 
some degree to those from foreign lands, which are so often 
placed as ornaments on our mantel-pieces. Though it had 
