196 8. R. PATTISON, F.G.S. 
diverge a little, and on doing so we find ourselves in the presence of 
rocks that are called Devonian, consisting principally of reddish-coloured 
limestones, slates, and shales, such as are found in the neighbourhood of 
Torquay and North Devon, and which extend into Cornwall. This is the 
Devonian strata, and below the Devonian we still pursue our way, across 
country, right into Wales, where we find a vast heaping up of mountain 
chains and other formations which are known as the Silurian, all still sloping 
inwards. Below these, again, we have an even grander mass of rocks called 
the Cambrian, and, dispersed amidst these, both, the Silurian and the 
Cambrian, exhibit also volcanic matter. The interpretation of this state 
of things must, of course, be, that each of these formations (proceeding 
westward), is beneath the other. I shall have to deal with four of these 
groups particularly, and, consequently, I have left out the minor layers, or 
strata, as not having anything to do with the subject of this paper. This 
brings me to that which I have put before you in the form of printed 
matter, and here I have to begin in a backward direction from that in which 
we have already travelled from London. We begin in fact where we just 
now left off, namely with the great Cambrian rocks :— 
PEDIGREE OF THE CORAL-REEFS OF ENGLAND. 
By 8. R. Parrison, F.G.S. 
\ N | ¥ propose to refer to the principal reefs of fossil coral 
in England, and examine their contents, and read the 
lessons they teach on the subject of Evolution. 
CAMBRIAN Rocks. 
The fine hilly district which stretches from the Irish 
Channel to the hills of the Welsh border, is principally com- 
posed of coarse slaty rocks, which were named Cambrian by 
the veteran geological chieftain, Professor Sedgwick. In 
these we find a few fossil corals, and abundant remains of 
creatures classed by naturalists as Hydroids and Bryozoa (or 
moss animals), but no reef builders. 
These Hydroids are the lowest corals, and Bryozoa are 
the lowest tribe of Molluscs. The former are lower by 
one step than the corals proper, and are so numerous in 
some of the Cambrian strata that whole floors and beds of 
limestone haye resulted from their decay, although the crea- 
tures are individually extremely minute (Graptolites). They 
are of the same class as the true corals; yet no one who 
