These are at present only
known by their teeth, or, in one instance, by one of the halves of
the lower jaw; and these indicate minute Quadrupeds, which present
greater affinities with the little Banded Anteater (_Myrmecobius
fasciatus_, fig. 158) of Australia than with any other living form.
If this conjecture be correct, these ancient Mammals belonged to
the order of the Marsupials or Pouched Quadrupeds (_Marsupialia_),
which are now exclusively confined to the Australian province,
South America, and the southern portion of North America. In the
Old World, the only known Triassic Mammals belong to the genus
_Microlestes_, and to the probably identical _Hypsiprymnopsis_ of
Professor Boyd Dawkins. The teeth of _Microlestes_ (fig. 157)
were originally discovered by Plieninger in 1847 in the "bone-bed"
which is characteristic of the summit of the Rhaetic series both
in Britain and on the continent of Europe; and the known remains
indicate two species. In Britain, teeth of _Microlestes_ have been
discovered by Mr Charles Moore in deposits of Upper Triassic age,
filling a fissure in the Carboniferous limestone near Frome, in
Somersetshire; and a molar tooth of _Hypsiprymnopsis_ was found
by Professor Boyd Dawkins in Rhaetic marls below the "bone-bed" at
Watchet, also in Somersetshire. In North America, lastly, there
has been found in strata of Triassic age one of the branches
of the lower jaw of a small Mammal, which has been described
under the name of _Dromatherium sylvestre_ (fig.
Pages:
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344