230 



HISTORICAL PALAEONTOLOGY. 



Finally, the Trias completes the tale of the great classes of 

 the Vertebrate sub-kingdom by presenting us with remains of 

 the first known of the true Quadrupeds or Mammalia. 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 



Fig. 158. The Banded Ant-eater (MyrmecoMiis fasciatua) of Australia. 



little Banded Ant-eater (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 Hypsi- 

 prymnopsis of Professor Boyd Dawkins. The teeth of Micro- 

 lestes (fig. 157) were originally discovered by Plieninger in 

 1847 in the " bone-bed " which is characteristic of the sum- 

 mit 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 Somerset- 

 shire; 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, 



