FOSSIL RUMINANTIA.
The study of fossil forms throws as much light upon the development of existing types of Ruminantia as it does in the case of the Perissodactyla. Until the last of the three great geologic epochs none have been found; whilst in the Tertiary strata from Eocene, Miocene, and Pliocene formations, numerous species are known, resembling existing types more closely as they are discovered in the more recently deposited strata.
As might be anticipated from what has been said above, and as is indicated in the table of classification of the Artiodactyla on page 336, Vol. II., the oldest forms of cloven-hoofed Mammalia must have been intermediate in structure between the Pigs and Ruminants. Such a creature existed at the close of the Eocene period in Chœropotamus, discovered first by the illustrious Cuvier in the palæontologically most interesting gypsum beds at Montmartre. Another specimen has also been found near Ryde, in the Isle of Wight. The creature was pig-like in size, and in the tuberculated structure of its grinders, the parts, together with the lower jaw, alone discovered as yet.
SKELETON OF THE IRISH ELK.
Hyopotamus, Dichobune, Xiphodon, and Cainotherium were four-toed Upper Eocene transitional forms approaching the Ruminants, but all possessing upper cutting-teeth, the last-named differing but little from the Deerlets. Oreodon is a genus of small pig-like animals, appearing first in the Miocene of North America, and evidently closely related to the Ruminantia. Sivatherium was a gigantic Ruminant with four horns in pairs, and evidently a trunk. Its remains are found in the Miocene deposits of the Sewalik hills of India. Deer, Oxen, Goats, and Sheep first appeared in the Pliocene period, as did Camels and Llamas. Antelopes and Giraffes existed earlier, namely, in the Late Miocene. It is a fact of interest that Camels are abundant in the Miocene and Pliocene of North America, whilst they are only very scantily distributed in the same strata of the Old World, Arabia and Asia being their sole living habitat.
Among the most interesting of the Pleistocene species which has been discovered in Great Britain is the gigantic Irish deer, a species originally included with the Elk, on account of the palmation and outward inclination of its huge antlers, in some specimens only a few inches less than eleven feet in span, and each more than five feet long in a straight line from burr to tip. In general form the antlers do not strikingly differ from those of the Common Fallow Deer. The brow-tyne is quite simple at its base, and generally slightly bifid at its extremity, there being no true “bez.” The beam is cylindroid as far as the insignificant “trez,” beyond which it is flattened out into a gigantic triangular expansion, or “palm,” with the free base developed into snags, usually about seven in number, and a fairly independent posterior tyne.
IRISH ELK. (Restored.)