Part 26 (1/2)

The geological place of the extinct Palaeotherium seems to have been in the first great fresh-water formation of the Eocene period, where it is chiefly found with its allies, of which several species have been found and identified by Cuvier. Dr. Buckland is not singular in thinking that they lived and died on the margins of lakes and rivers, as the Rhinoceros and Tapir do now. He is also of opinion that some retired into the water to die, and that the dead carcases of others may have been drifted into the deeper parts in seasons of flood.

The _Palaeotherium_ varied greatly in size, some species being as large as the Rhinoceros, while others ranged between the size of the Horse and that of a Hog or a Roe. The smaller Palaeotherium resembled the Tapir.

Less in size than a Goat, with slim and light legs, it must have been very common in the north of France, where it would browse on the gra.s.s of the wild prairies. Another species, the _P. minimum_, scarcely exceeded the Hare in size, and it probably had all the lightness and agility of that animal. It lived among the bushy thickets of the environs of Paris, in Auvergne, and elsewhere.

All these animals lived upon seeds and fruits, on the green twigs, or subterranean stems, and the succulent roots of the plants of the period.

They generally frequented the neighbourhood of fresh water.

[Ill.u.s.tration: Fig. 154.--Anoplotherium commune. One-twentieth natural size.]

The _Anoplotherium_ (from a??p???, _defenceless_, ??????, _animal_), had the posterior molar teeth a.n.a.logous to those of the Rhinoceros, the feet terminating in two great toes, forming an equally divided hoof, like that of the Ox and other Ruminants, and the tarsus of the toes nearly like those of the Camel. It was about the size of the a.s.s; its head was light; but what would distinguish it most must have been an enormous tail of at least three feet in length, and very thick at its junction with the body. This tail evidently served it as a rudder and propeller when swimming in the lakes or rivers, which it frequented, not to seize fish (for it was strictly herbivorous), but in search of roots and stems of succulent aquatic plants. ”Judging from its habits of swimming and diving,” says Cuvier, ”the Anoplotherium would have the hair smooth, like the otter; perhaps its skin was even half naked. It is not likely either that it had long ears, which would be inconvenient in its aquatic kind of life; and I am inclined to think that, in this respect, it resembled the Hippopotamus and other quadrupeds which frequent the water much.” To this description Cuvier had nothing more to add. His memoir upon the _pachydermatous fossils_ of Montmartre is accompanied by a design in outline of _Anoplotherium commune_, which has been closely followed in Fig. 154.

There were species of Anoplotherium of very small size. _A. leporinum_ (or the Hare-Anoplotherium), whose feet are evidently adapted for speed; _A. minimum_ and _A. obliquum_ were of still smaller dimensions; the last, especially, scarcely exceeded the size of a rat. Like the Water-rats, this species inhabited the banks of brooks and small rivers.

[Ill.u.s.tration: Fig. 155.--Xiphodon gracile.]

The _Xiphodon_ was about three feet in height at the withers, and generally about the size of the Chamois, but lighter in form, and with a smaller head. In proportion as the appearance of the _Anoplotherium commune_ was heavy and sluggish, so was that of _Xiphodon gracile_ graceful and active; light and agile as the Gazelle or the Goat, it would rapidly run round the marshes and ponds, depasturing on the aromatic herbs of the dry lands, or browsing on the sprouts of the young shrubs. ”Its course,” says Cuvier, in the memoir already quoted, ”was not embarra.s.sed by a long tail; but, like all active herbivorous animals, it was probably timid, and with large and very mobile ears, like those of the stag, announcing the slightest approach of danger.

Neither is there any doubt that its body was covered with short smooth hair; and consequently we only require to know its colour in order to paint it as it formerly existed in this country, where it has been dug up after so many ages.” Fig. 155 is a reproduction from the design in outline with which Cuvier accompanied the description of this animal, which he cla.s.ses with the Anoplotherium, and which has received in our days the name of _Xiphodon gracile_.

The gypsum-quarries of the environs of Paris include, moreover, the remains of other Pachyderms: the _Chaeropotamus_, or River-hog (from ?????? p?ta??), which has some a.n.a.logy with the living Pecari, though much larger; the _Adapis_, which reminds us, in its form, of the Hedgehog, of which, however, it was three times the size. It seems to have been a link between the Pachyderms and the Insectivorous Carnivora.

The _Lophiodon_, the size of which varied with the species, from that of the Rabbit to that of the Rhinoceros, was still more closely allied to the Tapir than to the Anoplotherium; it is found in the lower beds of the gypseous formation, that is to say in the ”Calcaire Grossier.”

A Parisian geologist, M. Desnoyers, librarian of the Museum of Natural History there, has discovered in the gypseous beds of the valley of Montmorency, and elsewhere in the neighbourhood of Paris, as at Pantin, Clichy, and Dammartin, the imprints of the footsteps of some Mammals, of which there seems to be some question, especially with regard to the Anoplotherium and Palaeotherium. Footprints of Turtles, Birds, and even of Carnivora, sometimes accompany these curious traces, which have a sort of almond-shape more or less lobed, according to the divisions of the hoof of the animal, and which recall to mind completely, in their mode of production and preservation, those imprints of the steps of the Labyrinthodon which have been mentioned as occurring in rocks of the Tria.s.sic period. This discovery is interesting, as it furnishes a means of comparison between the imprints and the animals which have produced them. It brings into view, as it were, the material traces left in their walks upon the soil by animals now annihilated, but who once occupied the mysterious sites of an earlier world. (See Fig. 1, p. 12.)

It is interesting to picture in imagination the vast pasturages of the Tertiary period swarming with Herbivora of all sizes. The country now surrounding the city of Paris belongs to the period in question, and not far from its gates, the woods and plains were crowded with ”game” of which the Parisian sportsman little dreams, but which would nevertheless singularly animate the earth at this distant epoch. The absence of great Carnivora explains the rapid increase of the agile and graceful denizens of the wood, whose race seems to have been so multiplied then, but which was ultimately annihilated by the ferocious beasts of prey which afterwards made their appearance.

The same novelty, riches, and variety which distinguished the Mammals of the Tertiary period extended to other cla.s.ses of animals. The cla.s.s of Birds, of which we can only name the most remarkable, was represented by the curious fossil known as the ”_Bird of Montmartre_.” The bones of other birds have been obtained from Hordwell, as well as the remains of quadrupeds. Among the latter the _Hyaenodon_, supposed to be the oldest known example of a true carnivorous animal in the series of British fossils, and the fossil Bat known as the _Vespertilio Parisiensis_.

Among Reptiles the Crocodile, which bears the name of Isle of Wight Alligator, _Crocodilus Toliapicus_. Among the Turtles the _Trionyx_, of which there is a fine specimen in the Museum of Natural History in Paris (Fig. 156).

[Ill.u.s.tration: Fig. 156.--Trionyx, or Turtle, of the Tertiary period.]

In the cla.s.s Fishes we now see the _Pleuronectes_, or flat-fish, of which _Platax altissimus_ and _Rhombus minimus_ are well-known examples.

Among the Crustaceans we see the earliest crabs. At the same time mult.i.tudes of new Mollusca make their appearance: _Oliva_, _Triton_, _Ca.s.sis_, _Harpa_, _Crepidula_, &c.

[Ill.u.s.tration: XXIII.--Ideal Landscape of the Eocene Period.]

The hitherto unknown forms of _Schizaster_ are remarkable among Echinoderms; the Zoophytes are also abundant, especially the _Foraminifera_, which seem to make up by their numbers for their deficiency in size. It was in this period, in the bosom of its seas, and far from sh.o.r.e, that the _Nummulites_ existed, whose calcareous envelopes play such a considerable part as the elements of some of the Tertiary formations. The sh.e.l.ly agglomerates of these Protozoan Rhizopods const.i.tute now very important rocks. The Nummulitic limestone forms, in the chain of the Pyrenees, entire mountains of great height; in Egypt it forms strata of considerable extent, and it is of these rocks that the ancient pyramids were built. What an enormous time must have been necessary to convert the remains of these little sh.e.l.ls into beds many hundreds of feet thick! The _Miliola_ were also so abundant in the Eocene seas as to const.i.tute the greater part of calcareous rocks[83] out of which Paris has been built. Agglomerated in this manner, these little sh.e.l.ls form the continuous beds of limestone which are quarried for building purposes in the environs of Paris, at Gentilly, Vaugirard, and Chatillon.

[83] Similar beds of Miliolite limestone are found in the Middle Bagshot beds on the coast of Suss.e.x, off Selsey--the only instance in England of the occurrence of such calcareous deposits of Middle Eocene age.--H. W. B.

On the opposite page we present, in PLATE XXIII., an imaginary landscape of the Eocene period. We remark amongst its vegetation a mixture of fossil species with others belonging to the present time. The Alders, the Wych-elms, and the Cypresses, mingle with _Flabellaria_; the Palms of extinct species. A great Bird--a wader, the _Tantalus_--occupies the projecting point of a rock on the right; the Turtle (_Trionyx_), floats on the river, in the midst of Nymphaeas, Nenuphars, and other aquatic plants; whilst a herd of Palaeotheria, Anoplotheria, and Xiphodon peacefully browse the gra.s.s of the natural meadows of this peaceful oasis.

With a general resemblance in their fossils, nothing can be more dissimilar, on the whole, than the lithological or mineral characters of the Eocene deposits of France and England; ”those of our own island,”

says Lyell,[84] ”being almost exclusively of mechanical origin--acc.u.mulations of mud, sand, and pebbles; while in the neighbourhood of Paris we find a great succession of strata composed of limestones, some of them siliceous, and of crystalline gypsum and siliceous sandstone, and sometimes of pure flint used for millstones.

Hence it is by no means an easy task to inst.i.tute an exact comparison between the various members of the English and French series. It is clear that, on the sites both of Paris and London, a continual change was going on in the fauna and flora by the coming in of new species and the dying out of others; and contemporaneous changes of geographical conditions were also in progress in consequence of the rising and sinking of the land and bottom of the sea. A particular subdivision, therefore, of time was occasionally represented in one area by land, in another by an estuary, in a third by sea; and even where the conditions were in both areas of a marine character, there was often shallow water in one, and deep sea in another, producing a want of agreement in the state of animal life.” The Eocene rocks, as developed in France and England, may be tabulated as follows, in descending order:--

[84] ”Elements of Geology,” p. 292.

English. French.

/ / Calcaire de la Beauce.

Hempstead beds.

Gres de Fontainebleau.