| From Owen. |
| Fig. 16.—Lower Jaw and Teeth of Amphilestes broderipi (twice nat. size). |
It will be observed from the figures of the lower jaws, which are in most cases the only parts known, that in many instances the number of cheek-teeth exceeds that found in modern marsupials except Myrmecobius. The latter has indeed been regarded as the direct descendant of these Mesozoic forms; but as already stated, in the opinion of Mr B. A. Bensley, this is incorrect. It may be added that the division of these teeth into premolars and molars in figs. 14 and 16 is based upon the view of Sir R. Owen, and is not altogether trustworthy, while the restoration of some of the missing teeth is more or less conjectural. As regards the affinities of the creatures to which these jaws belonged, Professor Osborn has referred the Triconodontidae and Amphitheriidae, together with the Curtodontidae (as represented by the English Purbeck Curtodon), to a primitive group of marsupials, while he has assigned the Amblotheriidae and Stylacodontidae to an ancestral assemblage of Insectivora. On the other hand, in the opinion of Professor H. Winge, a large number of these creatures are primitive monotremes. Besides the above, in the Trias of North America we have Dromotherium and Microconodon, extremely primitive forms, representing the family Dromotheriidae, and apparently showing decided traces of reptilian affinity. It may be added that a few traces of mammals have been obtained from the English Wealden, among which an incisor tooth foreshadows the rodent type.
Authorities.—The above article is partly based on that by Sir W. H. Flower in the 9th edition of this work. See also O. Thomas, Catalogue of Monotremata and Marsupialia in the British Museum (1888); “On Caenolestes, a Survivor of the Epanorthidae,” Proc. Zool. Soc. London (1895); J. D. Ogilby, Catalogue of Australian Mammals (Sydney, 1895); B. A. Bensley, “A Theory of the Origin and Evolution of the Australian Marsupialia,” American Naturalist (1901); “On the Evolution of the Australian Marsupialia, &c.,” Trans. Linn. Soc. (vol. ix., 1903); L. Dollo, “Arboreal Ancestry of Marsupials,” Miscell. Biologiques (Paris, 1899); B. Spencer, “Mammalia of the Horn Expedition” (1896); “Wynyardia, a Fossil Marsupial from Tasmania,” Proc. Zool. Soc. London (1900); J. P. Hill, “Contributions to the Morphology of the Female Urino-genital Organs in Marsupialia,” Proc. Linn. Soc. N. S. Wales, vols. xxiv. and xxv.; “Contributions to the Embryology of the Marsupialia,” Quart. Journ. Micr. Science, vol. xliii.; E. C. Stirling, “On Notoryctes typhlops,” Proc. Zool. Soc. London (1891); “Fossil Remains of Lake Cadibona,” Part I. Diprotodon, Mem. R. Soc. S. Australia (vol. i., 1889); R. Broom, “On the Affinities of Thylacoleo,” Proc. Linn. Soc. N. S. Wales (1898); H. F. Osborn, “Mesozoic Mammalia,” Journ. Acad. Nat. Sci. Philadelphia (vol. ix., 1888); E. S. Goodrich, “On the Fossil Mammalia from the Stonesfield Slate,” Quart. Journ. Micr. Science (vol. xxxv., 1894).
(R. L.*)
[1] The presence or absence of the corpus callosum has been much disputed; the latest researches, however, indicate its absence.
| Marsupial Mole (Notoryctes typhlops). |
MARSUPIAL MOLE (Noloryctes typhlops), the “Ur-quamata” of the natives, an aberrant polyprotodont from central South Australia, constituting a family (Noloryctidae). This is a small burrowing animal, of a pale golden-yellow colour, with long silky hair, a horny shield on the nose, and a stumpy leathery tail. The feet are five-toed, and the third and fourth toes of the front pair armed with enormous claws adapted for digging. Neither ear-conches nor eyes are visible externally. There are but three pairs of incisor teeth in each jaw, and the upper molars are tricuspid. This animal spends most of its time burrowing in the sand in search of insects and their larvae, but occasionally makes its appearance on the surface.