A Pictorial Atlas of Fossil Remains, consisting of coloured illustrations selected from Parkinson's "Organic remains of a former world," and Artis's "Antediluvian phytology."

by Gideon Algernon Mantell

Of these last, 575 species inhabit tropical seas, 350 the seas of temperate, and 75 the seas of cold climates.

[XIII.] Fossil Elk of Ireland, or Cervus megaloceros. ([Plate LXXI.])—The shell-marls of Ireland contain in abundance the bones of an animal, which like the Dodo, was once contemporary with the human species, but has long been extinct: the last individuals of the race were, in all probability, exterminated by the early Celtic tribes. The remains of this noble creature generally occur in the deposits of marl that underlie the peat-bogs, which are apparently, like those of Scotland, the sites of ancient lakes or bays. In Curragh immense quantities of these bones lie within a small area; the skeletons appear to be entire, and are found with the skull elevated, and the antlers thrown back on the shoulders, as if a small herd of these Elks had sought refuge in the marshes, and had been engulfed in the morass, in the same manner as the Mastodons of America. (See description of [Plate LXXIV.], ante, p. 167.)

This creature far exceeded in magnitude any living species of elk or deer. The skeleton is upwards often feet in height to the top of the skull, and the antlers are from ten to fourteen feet from one extremity to the other. The fine perfect skeletons in the British Museum, College of Surgeons, and in the Museum at Edinburgh, render a particular description unnecessary. The bones are generally well preserved, of a dark brown colour, with patches of blue phosphate of iron. In some instances they are in so fresh a condition, that the hollows of the long bones contain marrow having the appearance of fresh suet. Remains of this majestic animal have been found collocated with ancient sepulchral urns, stone implements, and rude canoes, in such manner, as to leave no doubt that this now extinct deer was coeval with the early human inhabitants of these Islands. Its bones and antlers have been found at Walton, in Essex, associated with the remains of the Mammoth, or fossil elephant.[122]

[122] Wonders of Geology, p. 134.

[XIV.] Fossil Infusoria—Infusorial Earths.—In the note on Foraminifera some account is given of various rocks composed of the fossil remains of those minute animals; but the durable relics of the yet more infinitesimal organisms designated by the terms Infusoria, or Infusorial animalcules, form deposits of equal interest and importance. Strata of great extent and thickness are wholly, or in great part, made up of innumerable layers, consisting of the aggregated siliceous cases or shields of Infusoria: and similar structures are found to be the chief constituents of the white earthy deposits of lakes, rivers, and basins of brackish water, in every part of the world.

Slowly, imperceptibly, but incessantly, are the vital energies of the feeblest and minutest animal and vegetable existences separating from the element in which they live, the most enduring of mineral substances, silex—fabricating it into structures of the most exquisite forms and sculpturing, and thus adding to the accumulations of countless ages, which make up the sedimentary strata of the crust of the globe.

In the "Medals of Creation"[123] will be found a summary of what was then known as to the formation and composition of many tertiary deposits which the indefatigable Ehrenberg, Dr. Bailey, and other eminent observers, had carefully investigated and described. The five years that have since elapsed have been fruitful in results of the most important and interesting character; from every quarter of the world, from the loftiest mountain peaks, and from the deepest recesses of the ocean which the plummet can reach, from the ashes of volcanoes and from the snow of the glaciers, the durable remains of Infusoria have been obtained. That excellent scientific periodical, Silliman's American Journal, contains numerous interesting communications on this subject from the eminent chemical professor of the Military College at West Point, Dr. J. W. Bailey; and the labours of Mr. Bowerbank, Williamson, and other active members of the Microscopical Society of London, have yielded much interesting information on the infusorial deposits of our own country.

[123] Medals of Creation, vol. i. p. 211.

The present note will be restricted to remarks on the nature of the organisms which enter so largely into the composition of certain tertiary deposits; since the opinion once entertained of the animal nature of many infusoria, now regarded as true vegetables, materially affects the geological conclusions respecting the persistence of certain species of organisms through long periods of time, during which the mollusca, zoophytes, &c. underwent repeated mutations both in the species and genera. Thus, for example, the polierschiefer, or polishing-slate of Bilin, and the berghmehl of Tuscany, are described by Ehrenberg as masses of the siliceous shells of animalcules of such extreme minuteness, that a cubic inch of the stone contains upwards of forty millions; the infusorial earth of Richmond, in Virginia, in like manner, is stated to be made up of the siliceous skeletons of animalcules of infinitesimal minuteness. But later investigations have (I conceive) satisfactorily established, that the greater part of these fossil organisms belongs to the vegetable and not to the animal kingdom.[124] The whole of the figures in [Plate IV.] of the "Medals of Creation," described as living Infusoria, on the authority of Ehrenberg, are undoubted vegetables, belonging to the great botanical groups called Diatomaceæ (from the angular segments into which they separate by partial division), and Desmidiaceæ.[125] The entire family of Bacillaria belongs to this group. These simplest forms of vegetable structures abound in every lake or stream of fresh and brackish water, in every pool, or bay, and throughout the ocean, from the equator to the poles; they secrete siliceous envelopes, which present an endless variety of form and structure, and after the death and decomposition of the perishable tissues of the plants, remain as perfectly transparent colourless shields of pure silica; such are the Gaillonellæ, Euastra, Closteria, Naviculæ, Synhedræ, Podospheniæ, Xanthidia, &c., which constitute so large a proportion of the infusorial earths described by Ehrenberg and other authors.[126]

[124] In my little work on Recent Infusoria, entitled "Thoughts on Animalcules, or a Glimpse of the Invisible World revealed by the Microscope," I have expressed my conviction of the vegetable nature of these organisms, as a reason for omitting figures and descriptions of any of the species in a work on living fresh-water animalcules.