

S 





k 



t 



s are 



'% 

 8 eat. 



rre- 



i or 



ofthe 





-km- 



oitais 



todiml 



cial ac- 

 i bloc' 



f to 



ijloci 





1 



m 



a 



has 



$ above 



In cob- 



liaTing 



r, 



so 



as 



ttro 



feci 





.tits 



aU' 



a 





Ch. XL] 



CLIMATE OF THE SILURIAN PEEIOD. 



231 



difficult to decide in many 

 action many of the effects al 



to have been due. 



Some 



from 



may 



tened, and scratched by glacial action, before they were trans- 

 ported to their present site. But although inclined to adopt 

 this explanation as 



think 



m0 re evidence must be obtained before we can feel perfectly 



mar 



origin 



>/ 



When 



climate of the Silurian and older formations, we find our- 



some impor 



emams 



formations of later date. Reptiles fail us entirely, as in the 

 Devonian rocks ; fish are wanting, except a few remains in 



■I - tt o:i,,-^^-r, . ,vP T%1ar.+a +Lpva nrfi nnnp. a,nd we must 



form 



the climate from those genera of invertebrate animals of 

 which there is a great profusion, but which usually in the 



om 



The large chambered cephalopods, the corals, and the crinoids 



members 



similar 



hemisphere, and a somewhat 



from 



Concluding remarks on climate.— The result then of our ex- 

 amination in this and in the preceding chapter ofthe organic 

 and inorganic evidence relating to the climate of successive 



warmer 



temperature generally prevailed in the northern hemisphere 

 from the 30th parallel of latitude to the pole than that now 

 experienced. In the Pliocene era the fauna and flora of Cen- 

 tral Europe were sub-tropical, and a vegetation resembling 

 that now seen in Northern Europe extended into the arctic 

 regions as far as they have been yet explored, and probably 

 reached the pole itself. In the Secondary or Mesozoic ages, 

 the predominance of reptile life, and the general character of 



