DEVONIAN SYSTEM. 159 
obtained, one of which is a huge kind of crab, sometimes six feet long, 
with terrible-looking toothed claws, called the Pterygotus! or ear-wing. 
Reptiles are also found, two very large lizards being most frequent. 
But by far the most numerous specimens of ancient life are gigantic 
fishes. These creatures are all covered with hard bony scales, burnished 
with enamel, with fierce teeth, and great fins armed with long sharp 
spines, with which they defended themselves or attacked their enemies. 

Fig. 85.—Old Red Sandstone Fishes. 
These fishes have received different names, according to peculiarities in 
their structure or appearance, and have been brilliantly described by 
Hugh Miller, who, when cutting the Old Red Sandstone as a mason, 
had his attention first drawn to geology by the brilliancy of their scaly 
armour. 
Scenery of Period.—The wide oceans in which the thin fine-grained 
flags were deposited must have been smooth and tranquil. Round the 
coral islands that rose in its gleaming waters coursed huge fierce 
fishes. The sandy shores became the coarser sandstone. Within tide- 
mark, numerous great crabs lived, and caught their prey in their toothed 
claws; shrimp-like creatures danced over the sands, and in them worms 
burrowed ; the waves ebbed and flowed, leaving their ripple-marks on the 
rocks we now see; gravel beaches fringed the shore, where the surges 
rounded the pebbles and rolled the stones, creating our conglomerates ; 
: 
1 Pteron, a wing, and ous, otos, the ear. 
