"The Pteropods, among Mollusks, were much larger than the modern species of the tribe. The Trilobites even of the Lower Cambrian comprise species as large as living Crustaceans. The Ostrapods are generally larger than those of recent times."[79]
Again, in speaking of the general character of the Cambrian fossils, he says:
"The types of the early Cambrian are mostly identical with those now represented in existing seas, and although inferior in general as to grade [in the "Phylogenic series">[, they bear no marks of imperfect or stunted growth from unfit or foul surroundings." (p. 485.)
The well known Mollusk, Maclurea magna, which is so enormously abundant in the Silurian, is often eight inches in diameter, and the astounding Cephalopod genus, Endoceras, consisting of twenty species, found only in two divisions of the Lower Silurian, has left shells over a foot in diameter, and ten or twelve feet long!
Of the fishes of the Devonian we have, among other remarks of a similar character, the following:
"The Dipnoans, or 'Lung-fishes,' were represented by gigantic species called by Newberry Dinichthys and Titanichthys, from their size and formidable dental armature.... A still larger species is the Titanichthys clarki of Newberry, in which the head was four feet or more broad, the lower jaw a yard long. This jaw was shaped posteriorly like an oar blade, and anteriorly was turned upward like a sled runner."[80]
One of the ancient Eurypterids from the Old Red Sandstone of Europe has a length of six feet, which is more than three times that of any Crustacean now living. While a gigantic Isopod Crustacean from the same strata had a leg the basal joint of which was three inches long, and three-quarters of an inch through, which is larger than the whole body of any modern species.
The ancient "Horse-tails," "Ground-pines," Ferns and Cycads were trees from 30 to 90 feet high, and their carbonized stems and leaves make up many of our largest and best beds of coal. Compared with them the modern representatives are mere herbs or shrubbery.
Of the gigantic insects of the Devonian and Carboniferous beds we might make similar remarks. Some of the ancient locusts had an expanse of wing of over seven inches; while many of the ancient Dragon-flies had bodies from a foot to sixteen inches long, with wings a foot long and over two feet in spread from tip to tip.
Here is James Geikie's summary of the leading types of the Palaeozoic: