V A GLIMPSE INTO THE PAST 129 



developed forms of life which originated in other 

 and more northern lands after Australia had 

 become isolated. The wonderful Marsupial fauna 

 of Australia, including the most diverse creatures 

 adapted for every sort of terrestrial existence, 

 are represented in the late Mesozoic and early 

 Tertiary periods of Europe and North America 

 by closely related though more generalized types, 

 which are amongst the most ancient mammals 

 known, and they probably gave rise on the one 

 hand to the modern Marsupials, which now only 

 survive in Southern America and Australia, and 

 to the Placental Mammals, which now range over 

 the whole world but are so poorly represented 

 in Australia. Other forms of life which were 

 once world-wide in their distribution seem to 

 have survived in Australia without development 

 or divergence into new types ; such are the 

 Ceratodus or Lung fish of a few Queensland 

 streams, which lived practically in its present 

 form in the Devonian Seas of the northern hemi- 

 sphere ; the Mussel Trigonia (Fig. 2, p. 14), a scarcely 

 modified descendant of the common Jurassic and 

 Cretaceous fossils that are found not only in the 

 northern hemisphere, but in Patagonia and at the 

 Cape ; the Anaspides or Mountain Shrimp of 

 Tasmania, whose effigy is stamped upon the 

 Permian and Carboniferous sandstones of Europe 

 and North America. These few instances of very 

 ancient types that were once widely distributed 

 in the northern hemisphere and now only survive 



SMITH; N.T. T 



