Fig. 15.—Semiophorus Velicans.
From the limestone of Monte Bolca.
From these facts Geologists have been led to conclude:—that the strata in question were deposited on the bed of an ancient sea in which these fishes swam; that the waters of the sea were suddenly rendered noxious, probably by the eruption of volcanic matter; that the fishes in consequence perished in large numbers, and were then almost immediately embedded in the calcareous deposits of which the strata are composed. These views receive no small confirmation from a very remarkable phenomenon to which we may be allowed, in passing, to call attention. In the year 1831 a volcanic island was suddenly thrown up in the Mediterranean between Sicily and the African coast; and the waters of the sea were at the same time observed to be charged with a red mud over a very wide area, while hundreds of dead fish were seen floating on the surface. Is it not pretty plain that when the mud subsided many of the fish were enveloped in the deposit, and thus preserved to future times? If so, then, we should have an exact modern parallel to the fossil fishes of Monte Bolca. But for the present it is our purpose rather to describe facts than to develop theories.[74]
Near the town of Aix, the ancient capital of Provence, in the south of France, is a group of strata, consisting chiefly of Conglomerate, Marl, Gypsum, and Limestone, which has earned for itself no small fame in the annals of Geology. Besides many curious relics of an extinct vegetation, these strata yield also an abundance of Fossil Insects, which emerge from the rocky bed in which they have slept for ages, with a surprising freshness and a life-like reality. But the quarries of Aix, like those of Monte Bolca, are chiefly famous for their Fossil Fish. And in this case, too, as in the former, it would seem as if vast multitudes had suddenly perished together from some mysterious cause, and were then as suddenly entombed. They exhibit no mark of mechanical violence: and yet they are found, not unfrequently, crowded together as closely as they can fit, in every variety of position, on the same slab of limestone. A good example of such a block is represented in our woodcut.
Fig. 16.—Fossil Fish from Aix.
The White Chalk Rock of Sussex has been rendered classical to the students of Geology by the skilful and laborious researches of the late Doctor Mantell. Previous to his time the Fish of the Chalk were known only by their teeth and bones, which abounded in every quarry. But he succeeded in bringing to light many whole skeletons, and disengaging them without injury from their chalky envelopment. In many cases these Fossil Fish appear to have suffered little from compression: the body still retains its rounded form; and even the most delicate scales and fins are as little disturbed or distorted as if the original had been surrounded by soft Plaster of Paris while floating in the water. For many years Doctor Mantell devoted himself, with indefatigable zeal, to the gathering of these interesting remains; and his magnificent collection now adorns the Galleries of the British Museum. In the annexed illustration is figured a specimen belonging to one of the most abundant species. It is closely allied to the common perch; and is popularly called Johnny Dory by the quarrymen of Sussex, but is entitled Beryx Lewesiensis by the learned.[75]
Fig. 17.—Beryx Lewesiensis, from the Chalk, near Lewes.
From Fossil Fish we now turn to Fossil Reptiles. Many of our readers have, perhaps, heard or read something about an important group of rocks known by the name of the Lias. This formation is well developed in England, and has received much attention from Geologists. It stretches in a belt of varying width from Whitby on the coast of Yorkshire to Lyme Regis on the coast of Dorsetshire; passing in its course through the counties of Leicester, Warwick, Gloucester, and Somerset. It is composed chiefly of Limestone, Marl, and Clay; and is celebrated for the number and size of its great Fossil Reptiles. Of these the most remarkable is the Ichthyosaurus or Fish-like Lizard.
This monster of the ancient seas combined, as its name denotes, the essential characters of a reptile with the form and habits of a fish. No such creature has been known to exist within historic times; nevertheless, all the various parts of its complicated structure have their analogies, more or less perfect, in the present creation. It had the head of a Lizard, the beak of a Porpoise, the teeth of a Crocodile, the back bone of a Fish, and the paddles of a Whale. In length it sometimes exceeded thirty feet; it had a short thick neck, an enormous stomach, a long and powerful tail. This last appendage, together with four great paddles or fins, constituted the chief organs of motion. But of all its parts the head was perhaps the most wonderful and characteristic. In the larger species the jaws were six feet long, and were armed with two rows of conical sharp-pointed teeth,—a hundred below, a hundred and ten above. The cavities in which the eyes were set measured often fourteen inches across, and the eyeballs themselves must have been larger than a man’s head.