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 Palæotherium. 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 Triassic 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 classes of animals. The class 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 _Hyænodon_, 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). [Illustration: Fig. 156.--Trionyx, or Turtle, of the Tertiary period.] In the class 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 multitudes of new Mollusca make their appearance: _Oliva_, _Triton_, _Cassis_, _Harpa_, _Crepidula_, &c.