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And, indeed, geology gives us an answer; but it reads contradictorily: It says yes, and it says no. Geology does show us forms of transition, and, indeed, most frequently in the lower classes of animals. Who that has once studied petrifactions, does not know the mass of forms of the terebratulæ, the belemnites, and the ammonites, in the Jura formation?
The remains of belemnites, trigoniae, and other marine shells, with fragments of wood, are common, and impressions of ferns, cycadeae, and other plants. The remains, also, of many genera of reptiles, such as Plesiosaur, Crocodile, and Pterodactyl, have been discovered in the same limestone.
It is on this very simple principle, and not upon imaginary laws of physiological correlation, about which, in most cases, we know nothing whatever, that the so-called restorations of the palaeontologist are based. Abundant illustrations of this truth will occur to every one who is familiar with palaeontology; none is more suitable than the case of the so-called Belemnites.
Among a great number of specimens of these Belemnites, however, it was soon observed that some showed a conical cavity at the blunt end; and, in still better preserved specimens, this cavity appeared to be divided into chambers by delicate saucer-shaped partitions, situated at regular intervals one above the other.
The belemnites are the internal shells of a sort of cuttle-fish which swam about in enormous numbers in the seas whose sediment forms our modern lias, oolite, and gault.
In what sense can 'Loligo' or 'Spirula' be said to be more specialized, or less embryonic, than 'Belemnites'; or the modern species of Lamellibranch and Gasteropod genera, than the Silurian species of the same genera?
The polypiaria were in such abundance as to form whole strata of themselves. The crinoidea and echinites were also extremely numerous. Shell mollusks, in hundreds of new species, occupied the bottoms of the seas of those ages, while of the swimming shell-fish, ammonites and belemnites, there were also many scores of varieties. The belemnite here calls for some particular notice.
New Genera of fossil Mammalia in the Middle Purbeck of Dorsetshire. Dirt-bed or ancient Soil. Fossils of the Purbeck Beds. Portland Stone and Fossils. Kimmeridge Clay. Lithographic Stone of Solenhofen. Archaeopteryx. Middle Oolite. Coral Rag. Nerinaea Limestone. Oxford Clay, Ammonites and Belemnites. Kelloway Rock. Lower, or Bath, Oolite. Great Plants of the Oolite. Oolite and Bradford Clay.
This is by no means an isolated fact; numerous shells from the department of Champagne had been taken to tire shores of the Lesse and the Meuse. At Solutre have been found belemnites, ammonites, and Miocene shells, which were certainly never native to that district, with pieces of rock-crystal from the Alps, and beads made of a jadeite of unknown origin.
A number of extinct animals, such as Ammonites and Belemnites, belong to this group their shells may be seen in any good museum; those of the Belemnites, as their name implies, are shaped like a dart; those of the Ammonites, like that of the beautiful Nautilus of our times; but the fisherfolk of Whitby, where they are found in numbers, say they are "snakes turned to stone."
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