ON THE PEDIGREE OF THE CORAL-REEFS OF ENGLAND. 197 
observes the structure of both could for a moment consider 
the one as the progenitor of the other. 
SILURIANS. 
Travelling thence eastwards, and passing the great volcanic 
region of Snowdonia, we find ourselves in a mountainous 
country of slate and sandstone, which was the theatre of 
the wanderings and wars of the ancient Silures, who con- 
tested the Roman advance. Sir Roderick Murchison, the 
explorer of this district, named the prevalent system of rock 
- here, Silurian, and the appellation, having been found conve- 
nient, has been applied to rocks of the same kind all over the 
world. 
Extending our journey towards Shrewsbury, through 
Wenlock, the traveller has by his side, for about thirty miles, 
a ridge of hills remarkably uniform, showing, wherever 
opened, limestone rock. On visiting any one of the numerous 
quarries on this hillside, the limestone is seen to be principally 
composed of rough blocks of fossil coral, embedded in shale 
and limestone. A very short study convinces the beholder 
that he is on a coral-reef of the old ocean, and that its growth 
and aspect must have been altogether like the description 
given of the great live reefs now existing in the Pacific 
Ocean. ‘There are 102 specimens of corals in these strata, of 
which the more numerous belong to the genera Favosites 
(honeycomb coral), and Halysites (sea-stone, of which the 
chain-coral is well known), Monticulipora (little-mound pores), 
and Syringopora (pipe-pores). All these forms are absolutely 
unknown to any preceding platform of life in the geological 
scale ; they burst at once on the stage. There are no traces 
of direct ancestors, nor shall we find, as we ascend, that they 
leave any successors displaying their exact form and fashion. 
Many genera of creatures are the same as in the succeeding 
rocks; but not one species. We can, however, perceive at 
a glance, that the old corals were as large, beautiful, and 
elaborate as any of the modern ones. 
Whence came these curious creatures, or rather tribes? 
Were they emigrants? ‘There is no evidence of this. Were 
they descendants of any previous form? The facts forbid 
the assumption. Like Minerva springing from the head of 
Jupiter, they rise up fully armed cap a pied. 
DEVONIANS. 
Diverging southwards on our journey—or, rather voyage 
across ancient oceans—we come to the rich marbled rocks cut 
