[755] See Hist. Brit. Foss. Mam. p. 184, &c.; Quart. Journ. Geol. Soc. vol. iv. p. 42; and Petrif. p. 357.
FOSSIL MARSUPIALIA.
VI. Fossil Marsupialia.[756]—That the remains of an extinct species of gigantic Kangaroo should be found in the fissures of the rocks and in the caverns of Australia, a country in which marsupial animals are the principal existing mammalia, is a fact that will not excite much surprise; but that beings of this remarkable type of organization should ever have inhabited the countries situated in the latitude of the European continent and of Great Britain, would never have been suspected, but for the researches of the geologist. The fossil remains of this class discovered in Australia[757] occur in the pleistocene deposits of Darling Downs, Melbourne, &c. and in fissures and caves in the limestone of Wellington Valley, imbedded in red ochreous loam, and are often incrusted by stalactitic concretions. One of the species exceeds the largest existing Kangaroo, and its bones are associated with those of the Wombat, and other marsupial animals (Ly. p. 155).
[756] Marsupialia; animals that carry their young in a pouch (marsupium), as the Kangaroo.
[757] Rep. Brit. Assoc. 1844, p. 223.
A species of Didelphys (Opossum) has been discovered in the gypseous limestone of Montmartre, and is figured and described by Cuvier (Oss. Foss. vol. iii. pl. lxxi.; see also Brit. Foss. Mam. p. 76). It consists of a considerable part of the skeleton of a small animal, imbedded in gypsum; the block containing the specimen has been split asunder, and some of the bones are attached to the surface of one moiety, and the remainder to the other. From the character of the jaws and teeth, Cuvier pronounced that the animal was related to the Opossum, and confidently predicted that the two peculiar bones which support the pouch in these animals would be found attached to the fore-part of the pelvis; accordingly he chiselled away the stone, and disclosed these marsupial bones; thus proving the truth of those laws of correlation of structure, which he was the first to enunciate and establish. But as there are true marsupials in which the ossa marsupialia are merely rudimentary, for example, in the Dog-headed Opossum, or "Hyæna" of the Tasmanian colonists (Thylacinus Harrisii), in which they are merely two small, oblong, flattened fibro-cartilages, imbedded in the internal pillars of the abdominal rings, and are only six lines long and three or four lines broad,—it follows that in a fossil state the pelvis of a true marsupial animal may be destitute of those appendages which are commonly supposed to be an essential character of the marsupial skeleton. Thus the fossil pelvis of the Thylacinus, had that species been long ago, as it is soon likely to be, extinct, would not have afforded the certain evidence of its marsupial character to which Cuvier triumphantly appealed in demonstration of the Didelphys of the gypsum quarries of Montmartre; yet the Thylacinus would not therefore have been less essentially a marsupial animal.[758]
[758] See Prof. Owen, Zoological Society’s Proceedings, Dec. 1844.
FOSSIL MAMMALIA.
In the Eocene sand at Kyson, near Woodbridge, in Suffolk, among other mammalian remains (Ly. p. 203), Mr. Colchester, of Ipswich, whose researches have been rewarded by many interesting fossils, found a fragment of the jaw, with one premolar tooth having two fangs, of a small animal (Didelphys Colchesteri, Owen); and which Mr. Charlesworth (Curator of the Philosophical Institution of York) ascertained to belong to a marsupial animal allied to the Opossum.[759]