244 



MAMMALIA. 



wholly cut off from food during- this period. Thus the gray scjuir- 

 rel, being able to find a certain amount of sustenance when the 

 around is covered with snow, remains dormant during severe cold 

 only ; and the chipmunk, which lays up a great store of provision, 

 frequently awakes to eat, and is at all times easily aroused ; while 

 the Woodchuck, whose food is of such a nature that he can neither 

 gather a suppl\- for winter's use, nor find an\- were he to go in 

 search of it, must needs sleep long and soundly or starve. 



The Woodchuck and the flying scjuirrel occupy the; two extremes 

 of the family to which both belong, while the ground s([uirrels and 

 spermophiles hold intermediate positions. The tl)'ing s(|uirrel is 

 the most highly specialized form, showing the most perfect adapta- 

 tion of structure to habit ; while the Woodchuck must at present 

 be regarded as the most generalized type of the living members of 

 the grou[). These animals are so widel\- different that, taken 

 alone, they wouKl naturall\- be regarded as pertaining to separate 

 families ; but a careful stud\- of the nunierous interniediate forms 

 not only proves this \'iew to be incorrect, but also shows that the 

 gradation of connecting species is so complete that it is even diffi- 

 cidt, in niany cases, to draw the line between genera. 



The Woodchuck lacks the grace and agility of the arboreal 

 squirrels, but his heavy body and powerful paws are well adapted 

 to his terrestrial mode of life. Both animals are modified, but to 

 widely different ends. 



Woodchucks are both nocturnal and diurnal, the periods of feed- 

 ing being determined, in a general way, by the time of the year, 

 the weather, and the proximit}' and nature of enemies. In summer, 

 throughout the farming districts, they commonl)- leave their bur- 

 rows earl)' in the morning, late in the afternoon, and during mocjn- 

 lio'ht niehts ; but may sometimes be found abroad at all hours. As 

 autumn approaches, and they become! more and more fat and sleep)', 

 they usually appear only in fine weather, and then but for a few 

 hours in the hottest part of the afternoon. 



