12 L. W. SACKETT 



adaptation. Throughout this discussion the forefeet of the 

 porcupine are referred to as hands, as they figure as such in 

 the experiments. The human hand, it will be remembered, has 

 three distinct lines, two transverse and one longitudinal. All 

 of these lines are equally plain in the paw of the monkey and 

 chimpanzee, and are well marked in the hand of the porcupine, 

 though the digit corresponding to the human thumb is wanting 

 in the latter case and the fingers move in unison with little or 

 no independence of the digits. In place of the external thumb 

 there is a knot or ball very much as would appear if the human 

 thumb were amputated at the second joint. An examination of 

 the skeleton shows a rudimentary toe or thumb perfectly artic- 

 ulated and armed with a claw. In one instance the hardened 

 claw was protruding half its length. The whole is beneath the 

 surface in most instances with only a cartilaginous scar show- 

 ing through the epidermis. This hardened, rounded ball serves 

 the animal very well in grasping and is more advantageous 

 than a thumb would be in walking. The hand is limited in 

 movements to the simultaneous flexing of the fingers and the 

 rotation through about 90 degrees by means of the wrist and 

 forearm. This rotation is exactly the adaptation necessary for 

 the porcupine in its change from walking on a horizontal sur- 

 face to climbing the perpendicular trunk of a tree. 



The hind feet have five claws and very broad flat soles with 

 little of the possibility of movement seen in the hand. They 

 are adapted best for walking, or standing and sitting in an 

 erect posture. 



The Naturalists and the Porcupine. — Even the more careful 

 naturalists have honestly misjudged the behavior of the porcu- 

 pine in many ways. In his study of the quadrupeds of North 

 America, Audubon (3) finds the Canada porcupine the slowest 

 of them all. Burroughs (6) uses this sluggishness to account 

 for both the physical weakness and the stupidity of the porcu- 

 pine. Bearing on the first point he cites the instance in which 

 he struck one of them on the nose with a rotten stick merely 

 for the purpose of confusing it, killing it with a blow which he 

 thinks a wood-chuck or a coon would hardly have regarded at 

 all. Then he argues: "Thus does the easy passive mode of 

 defence of the porcupine not only dull its wits but makes frail ^ 

 and brittle the thread of its life. He has no struggles or battles 



