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54 THE TESTIMONY OF THE ROCKS. 
new forms often appearing suddenly and together. The 
very simplest known fossils, the trilobites, of which nearly 
a hundred species are known in America alone, and 
certain cephalopods (sea snails) are animals highly com- 
plex in structure and regarded by Le Conte as “hardly 
lower than the middle of the animal scale.” The trilo- 
bites possess well developed compound eyes and_ the 
cephalopods have simple eyes, almost as complex as 
the eyes of man, possess a well defined stomach, a systemic 
heart, a liver, and a highly developed nervous system. 
Observe, that these two highly organized forms of ani- 
mals, “hardly to be regarded as lower than the middle of 
the animal scale,” are the very “oldest” animals found in 
fossil form! In other words, of at least one ‘half of the 
total progress of the animal kingdom every vestige is 
lost. If we turn a few pages in Dana’s “Manual” we 
find in the sandstone of the “Devonian Era” gigantic 
species of fish. The entire record of evolution from the 
mollusk to the fish is lost!) There is not a single transi- 
tional form. These fishes have organs as complex and 
perfect as the fishes of to-day. Suddenly, in the “car- 
bonic age’ amphibia and reptiles appear, and then come, 
in the “Triassic” the huge reptiles known as dinosaurs. 
Insects and scorpions have been found in the “Silurian”. 
They stand among the highest of even living articulates, 
and they are the “oldest” known airbreathing animals. 
“We seek in vain for the progenitors of these highly 
organized articulates or for some conceivable method by 
which their wings and special breathing apparatus could 
have evolved. We do not know that these first in- 
sects and scorpions have made any material progress 
through all the ages.” ( Fairhurst.) 
Professor Huxley in delivering the anniversary ad- 
dress to the Geological Society for 1870, quotes the fol- 
