128 THE MIDDLE PAST. 



more conclusive teeth, jaws, and other fragments pointing 

 unmistakably to small marsupial quadrupeds (microlestes, 

 dromatherium, &c.), which find their nearest analogues in 

 the wombats and kangaroo-rats of Australia. 



Such is the scanty and imperfect record of triassic life, 

 as preserved in the variegated sandstones, the muschelkalk, 

 and saliferous marls of Europe and North America. This 

 imperfection may arise, partly from the circumscribed and 

 varying seas of deposit, partly from the saline peculiarities 

 of their waters, and partly from the unsuitable nature of 

 their sediments for the preservation of organic structure ; 

 but from whatever cause, we are clearly not entitled to 

 generalise from these limited areas to the universal distri- 

 bution of triassic vitality. On the contrary, the steady 

 creational advance to higher and higher facies of life, pre- 

 suppose not only an extensive series of graclational species, 

 but a numerical exuberance through which the law of spe- 

 cific advancement could operate. And even now, in the 

 St Cassian beds of the Austrian Alps, we are not without 

 evidence of many new and connecting forms genera which 

 unite the palaeozoic and niesozoic into one continuous life- 

 stream, and forbid the unphilosophical idea of creational 

 breaks in the evolution of vitality. As the facts stand 

 (and we know little beyond a few unconnected belts of de- 

 posit in the northern hemisphere), the triassic flora points 

 to insular rather than to continental conditions, and to an 

 arid rather than to a genial climate ; its marine fauna, in 

 harmony with these conditions, points rather to circum- 

 scribed seas than to gigantic estuaries ; whilst its terrestrial 

 animals indicate the thirsty desert rather than the fertile 

 plain, and sun-baked muddy creeks rather than the ex- 

 posed shores of the open ocean. 



The Oolitic era, to which we next turn, presents geograph- 



