PRIMITIVE DIVERSITY AND NUMBERS OF ANIMALS IN GEOLOGICAL TIMES.
Professor Agassiz considers that the very fact of certain stratified rocks, even among the oldest formations, being almost entirely made up of fragments of organised beings, should long ago have satisfied the most sceptical that both animal and vegetable life were as active and profusely scattered upon the whole globe at all times, and during all geological periods, as they are now. No coral reef in the Pacific contains a larger amount of organic débris than some of the limestone deposits of the tertiary, of the cretaceous, or of the oolitic, nay even of the paleozoic period; and the whole vegetable carpet covering the present surface of the globe, even if we were to consider only the luxuriant vegetation of the tropics, leaving entirely out of consideration the entire expanse of the ocean, as well as those tracts of land where, under less favourable circumstances, the growth of plants is more reduced,—would not form one single seam of workable coal to be compared to the many thick beds contained in the rocks of the carboniferous period alone.
ENGLAND IN THE EOCENE PERIOD.
Eocene is Sir Charles Lyell’s term for the lowest group of the Tertiary system in which the dawn of recent life appears; and any one who wishes to realise what was the aspect presented by this country during the Eocene period, need only go to Sheerness. If, leaving that place behind him, he walks down the Thames, keeping close to the edge of the water, he will find whole bushels of pyritised pieces of twigs and fruits. These fruits and twigs belong to plants nearly allied to the screw-pine and custard-apple, and to various species of palms and spice-trees which now flourish in the Eastern Archipelago. At the time they were washed down from some neighbouring land, not only crocodilian reptiles, but sharks and innumerable turtles, inhabited a sea or estuary which now forms part of the London district; and huge boa-constrictors glided amongst the trees which fringed the adjoining shores.
Countless as are the ages which intervened between the Eocene period and the time when the little jawbones of Stonesfield were washed down to the place where they were to await the day when science should bring them again to light, not one mammalian genus which now lives upon our plane has been discovered amongst Eocene strata. We have existing families, but nothing more.—Professor Owen.
FOOD OF THE IGUANODON.
Dr. Mantell, from the examination of the anterior part of the right side of the lower jaw of an Iguanodon discovered in a quarry in Tilgate Forest, Sussex, has detected an extraordinary deviation from all known types of reptilian organisation, and which could not have been predicated; namely, that this colossal reptile, which equalled in bulk the gigantic Edentata of South America, and like them was destined to obtain support from comminuted vegetable substances, was also furnished with a large prehensile tongue and fleshy lips, to serve as instruments for seizing and cropping the foliage and branches of trees; while the arrangement of the teeth as in the ruminants, and their internal structure, which resembles that of the molars of the sloth tribe in the vascularity of the dentine, indicate adaptations for the same purpose.
Among the physiological phenomena revealed by paleontology, there is not a more remarkable one than this modification of the type of organisation peculiar to the class of reptiles to meet the conditions required by the economy of a lizard placed under similar physical relations; and destined to effect the same general purpose in the scheme of nature as the colossal Edentata of former ages and the large herbivorous mammalia of our own times.