32 THE MEDALS OF CREATION, Cuap. IT. 
and limestones ; the prevailing colour is a dull red. Shells, 
corals, and ganoid fishes, of a very peculiar type. Reptiles, 
(Teterreton ; Batrachians ? Chelonians ?); the most ancient 
reptilian remains hitherto discovered. Ferns, Lepidoden- 
drons, and other trees of the carboniferous flora; fluviatile 
plants with batrachian ova (?). 
Subdivisions :— 
1. Sandstone, quartzose conglomerates, and shale, with but few 
fossils. 
ow \,. ae Well 
2. Flagstones, marls, and concretionary limestones; provincially — 
termed corn-stones ; laminated reddish and greenish micaceous sand- 
stones (prov. tilestones). Peculiar genera of fish; orthocerata, and 
many species of marine shells. 
Obs.—The term Devonian, by which the series of strata compre- 
hended in this formation is now generally distinguished by geologists, 
was first proposed by Sir R. Murchison, as being more precise than 
the name formerly applied to this group. In Scotland, where the 
formation is of vast extent, it was first characterized by its peculiar 
ganoid fishes (Pterichthys, Coccosteus, Cephalaspis), and will pro- 
bably always there retain the original name of Old Red.* In 
Devonshire it is marked by the presence of shells of a character in- 
termediate between those of the Silurian and Carboniferous systems. 
The sandstones are in various states of induration, and when slaty, 
are employed for roofing. The red colour predominates in the marls, 
and is derived from peroxide of iron. The formation of these rocks 
has manifestly resulted from the waste of ancient slate rocks, the 
detritus of which is cemented together into coarse conglomerates. 
In South Devonshire (at Torquay, Babbicombe, &c.), beautiful coral- 
line marbles occur in this formation. 
THE SILURIAN System. (Wond. p. 765). Marine lime- 
stones, sandstones, shales, and calcareous flagstones, charac- 
terized by peculiar types of corals, crinoideans, mollusks, 
and crustaceans, constitute this important and extensive 
system of rocks ; the Grauwacké, or Transition series of the 
earlier geologists. 
* See the charming volume of Mr. Hugh Miller, entitled “The Old 
Red Sandstone, or New Walks in an Old Field.” 
