422 MANUAL OF THE ^lOLLUSCA. 



living at the Cape ; ClaveUa^ at the ^larquesas, and Pseudoiha, Trochita, and 

 species oiMurex^ whose recent analogues are found on the Western shores of 

 S, America. 



The freshwater shells of this period are Old-World forms ; Melanopsisi 

 Potainides, Lampania, 3hlanatna and Xemutura : whilst the laud-shells 

 form a group quite American ia character ; large species of Glandina and 

 Bulimus (with reflected lip) Ih(jaJomastoma {mumid), a Cyclotus (with its 

 operculum) like C. Jamaicensis, and the little Helix labyrmtlucus. 



Secondary Age. — la none of the older strata do w'e find indications of a 

 warmer climate having prevailed, in the latitude of England, than that which 

 marks the period of the London clay. And this is not more than can be 

 accounted for by such a cause as the flow of an equatorial current from the 

 direction of the Red Sea, until arrested by a continent to the south-west, as 

 supposed by Mr. Prestwich, in the region of the Azores. 



Some indications exist of a more moderate climate having obtained in 

 the north polar regions ; for remains of the Ichthyosaurus were foimd at 

 Exmouth Id. the furthest point reached by Sir E. Belcher's expedition. 



The peculiar physical conditions of the Chalk period are represented at 

 the present day, not so much by the Coral-sea, as by the ^gean., where cal- 

 careous mud, derived from the waste of the scaylia regions, is being rapidly 

 deposited in deep water. {Forbes). 



The Wealden period was styled the "Age of Reptiles" by Dr. Mantel), 

 who compared the state of England at that time with the present condition 

 of the Galapagos Islands. 



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

 cut by Prof. 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 com- 

 pared 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.* 



Pdceozoic Aye. — It has lately been suggested by Prof. Ramsay that 

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

 of the Permian Period ; and Mr. Page has endeavoured to apply the same 

 interpretation to phenomena of a much earlier date, in the old red sand-stone 

 of Scotland. t Geologists generally have abandoned the notion, once very pre- 

 valent, of a universal hioh temperature in the earliest periods; a notion which 



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

 wingless birds of New Zealand, Prof. Owen suizgestedthe notion of land having been 

 propagated like a wave throuijhout the vast interval between Connecticut and New 

 Zealand, since the Triassic period. 



+ See also the Rev. J. G. Cumming's " Isle of Man," ^1819), p. 89. 



