V 



I 



t 



k 



* 





f 



arctic 



lie k 



a 



meriea. 

 1 lasted 



a time 

 •T m 



I 



ra of a 



•adually 



id mam- 

 mtinent 



iflg 



[cli once 









:P 



J 



Ch. X.] 



TRANSITION FROM WARMER TO COLDER CLIMATES. 199 



colder climate. — When 



pass beyond the 



ages when a 



colder temperature prevailed, and, receding a step farther 

 into the past, examine the fossils of the British Pliocene 



member 



straw*, wc «"«■ — — -~ 



very interesting proofs of a climate warmer than that now 

 I-^Utio" in England, and more resembling that of the 



prevailing in England, 



Mediterranean 



As we ascend in the series, the shells of 



Nor 



folk and Suffolk, are seen to consist less and less oi southern 

 species, while the number of northern forms is always aug- 

 menting, until in the uppermost or newest groups, in which 

 almost "all the shells are of living species, the fauna is ver> 

 arctic in character, and that even in the 52nd and 

 degrees of North latitude, as before mentioned, p. 197.* 



T 



o4th 



Pliocene strata of 



The Pliocene strata of Italy , 



commonly called sub-Apennine, point in like manner to a 



warm climate. 



exam 



fossil shells of 



Sienna, Parma, and Asti, as are of species now inhabiting the 

 Mediterranean and the Indian Ocean, correspond in size with 



of the two seas, those 



mer 



Mediterr 



in their growth, as if deprived of the favourable conditions 



t 



may 



also be observed, that the extinct species of the sub-Apen- 

 nine fauna belong, in great part, to forms which are now most 

 largely developed in equinoctial regions, as, for example, the 



Pleurotoma 



Warm climate of 



The next step 

 monuments of 



Miocene 



marine formations 



era a third or more of the testacea belong to living species, 



more 



latitudes, and associated also with many genera now charac- 



warmer regions 



Although in Great Britain strata 



~ " ium 



ot this period are entirely wanting, they occur m .Belgium 

 and North Germany, where they contain shells of the genera 



* Elements of GeoL, pp. 198, 204. 

 ^it, of 1865. 



t Professors Guidotti of Parma, and this point. 



Bonelli of Turin, pointed out to me, in 

 1828, many examples in confirmation of 



.6- 



