MISCELLANEOUS EXAMPLES 123 



" Old World " look, and are truly ancient. They spend the larger 

 part of their time upside down in the manner represented in the 

 drawings. They are arboreal and nocturnal animals that come 

 down to earth in search of food when things are quieter below, and 

 will wander for considerable distances, walking slowly on the outer 

 borders of their feet and the feet turned in. 



These being the few facts of their lives which concern the 

 present subject one comes, as usual, to interpretation. These tree- 

 sloths are descended from an older form that inhabited the ground, 



Key/ 



Fig. 48. — Two toed sloth, showing action of gravity upon the 



long thick hairs. 



so that the present mode of life, which is so largely arboreal, has 

 been acquired by dint of long years of struggle and adaptation to 

 bitter needs. It seems hardly reasonable to call in the aid of 

 selection for the production of its singular disposition of hair though 

 that factor ruled in the production of its arboreal habit. It is 

 almost flying in the face of common sense to attribute this upward, or 

 downward (according to one's point of view) singular arrangement 

 to anything but the effects of gravity upon its long hairs. If it be 

 not so, it looks a remarkable likely solution of this small problem. 



