No. 479] EXTINCTIOX OF ^rAMMALIA 795 



like the severe winters and damp summers returning after a series 

 of years in the temperate zone, may affect the proportional numl)ers 

 of ahnost all classes of animals and plants, and probably prove 

 fatal to the existence of many which would otherwise thrive there; 

 while, on the contrary, the saiiu^ (xcunviiccs van s( aic(>ly fail to 

 be favourable to certain sjiccio wliich. if (icj)rivc(l of such aid, 

 might not maintain their ground." 



{To be continned) 



