98 Duncan—Miocene Beds of Antigua and Malta. 
pore were doubtless then, as now, reef-corals, and the genus 
Flabellum inhabited deep water; moreover the large genera 
Trochocyathus, Astroceenia, Styloceenia, and others are extinct. 
The corals offer, then, advantages to the paleontologist both in 
estimating the relative age of distinct strata, and in considering 
the physical conditions under which they were deposited. 
Coral-growth had the same laws then, and the same physical 
conditions regulated the distribution and persistence of certain 
genera, as during the recent period: there were areas where 
corals flourished in greater abundance than in others, and loca- 
lities where there was an extraordinary luxuriance of growth of 
some species, whose individuals were dwarfed in other and less 
favoured seas; and in the midst of the most prolific coral-seas 
there were spots where the polypes worked under disadvantages, 
and where a peculiar and adapted fauna existed. 
By comparing the coral-faune of the various Miocene strata 
of Europe, America, and Continental Asia, and by paying atten- 
tion to the present habits of the species and genera found re- 
presented in them, we can map out these areas of luxuriance, 
and also the localities where the coral-fauna has been influenced 
by external conditions unfavourable to the growth of certain 
species. Generally speaking, the European Miocene coral- 
fauna is less luxuriant than the West Indian; and it is remark- 
able that the formation in the Island of Antigua, which is 
characterized by a poverty of coral-growth, and by the predo- 
minance of genera and species that have small corallites, should 
resemble in this and many other particulars the lowest calea- 
reous bed of Malta. 
The unfavourable conditions which must have affected the 
coral-growth on the reef which afterwards became the ‘ Chert’ 
of Antigua, can be estimated by the quantity of dricted wood 
and brackish-water molluses which are found mingled with the 
silicified corals; and although these evidences of the former 
existence of more fresh water than was consistent with a 
luxuriant coral-growth are wanting at Malta, still the general 
inferiority of vigour in the European Miocene coral-fauna 
brings the dominant species of the lowest Maltese beds and of 
the Chert of Antigua into a very interesting relation. 
Geological History and: Relationships, of the Coral-bearing 
Strata of Antigua.—The Chert in the Island of Antigua lies 
unconformably upon the oldest calcareous strata, which latter 
have a considerable inclination ; and it is covered conformably 
by a vast marl.* The inclined strata dip towards the chert, 
* Nugent, Trans. Geol. Soc., Ist series, vol. v. p. 459, 1821. 
