DISTE'IBUTION OF THE MOLLTJSCA IN TIME. 133 



The peculiar physical conditions of the Chalk period are 

 represented at the present day, not so much by the Ooral Sea, 

 as by the JSigean, where calcareous mud, derived from the waste 

 of the scaglia regions, is being rapidly deposited in deep water. 

 {Forbes.) 



The Wealden period was styled the " Age of Eeptiles " by Dr. 

 Mantell, who compared the state of England at that time with 

 the present coEdition of the Galapagos Islands. 



The Oolitic period finds its parallel in Australia, as long since 

 pointed out by Professor Phillips, and the comparison holds 

 good to some extent, both for the Marine and Terrestrial 

 Faunas. 



The Trias, with its foot-prints of gigantic wingless birds, has 

 been compared with the state of the Mascarene Islands only a 

 few centuries ago, and with the New Zealand Fauna, where 

 birds are still the highest aboriginal inhabitants.* 



Palceozoic Age. — It has lately been shown by Professor Eamsay 

 that signs of glacial action may be traced in some of the trappean 

 conglomerates of the Permian and of the Devonian or Old Eed 

 Sandstone period in England ; and Mr. Page has endeavoured 

 to apply the same interpretation to phenomena of a similar cha- 

 racter in the Old Eed sandstone of Scotland, t Geologists gene- 

 rally have abandoned the notion, once very prevalent, of a 

 universal high temperature in the earliest periods ; a notion 

 which they had derived from the occurrence of certain fossil 

 plants, corals, and shells in high latitudes. 



The absence of remains of mammalia in the palseozoic forma- 

 tions, is at present a remarkable fact, but it is completely 

 paralleled in the great modern zoological province of the Pacific 

 Islands. 



Baron Humboldt has speculated on the possibility of some land 

 being yet discovered, where gigantic lichens and arborescent 

 mosses may be the princes of the vegetable kingdom. J If such 

 exist, to shadow the Paleeozoic age, its appropriate inhabitants 

 would be like the cavern-haunting Proteus, and the Silures 

 which find an asylum even in the craters of the Andes. 



What, then, is it which has chiefly determined the character 

 of the present zoological provinces ? What law, more powerful 

 than climate, more influential than soil, and food, and shelter ; 



* In a paper read before the British Association, on the subject of tlie great extinct 

 wingless bii'ds of New Zealand, Professor Owen suggested the notion of land having 

 been propagated like a wave tlu-oughout the vast interval between Connecticut and New 

 Zealand, since the Triassic period. 



t See also the Rev. J. G. Cumming's " Isle hi Man '' (1849), p. 89. 



X Views of Nature, p. 221. Bohn's ed. 



