94 COLIN CLOUT'S CALENDAR. 



mcntcc! l^y extensible folds of loose skin stretching 

 between the lej,^s or the finders. 



A ^roup which shows so much variety of specialisa- 

 tion for its peculiar functions is likely to be an old one ; 

 and in fact the squirrels rank amon^j our oldest surviv- 

 injr indigenous mammals. As a class, they date back as 

 far in geolojrical time as the lower miocenc ; and even 

 our pjif^lish species must have inhabited this country, 

 practically unchanj^ed in appearance or habits, for man)- 

 thousands of years, except when driven temporarily 

 southward by stress of passini^ glacial periods. 



