542 On the Effect of impacts and Strains _ [July, 
(From the American Naturalist, Fuly, 1881.) 
ON THE EFFECT OF IMPACTS AND STRAINS ON 
THE FEET OF MAMMALIA}! 
BY E. D. COPE, 
HE principal specializations in the structure of the feet of the 
Mammalia may be summarized as follows: 
I. The reduction of the number of the toes to one in the Peris- 
sodactyla (horses, etc.), and two in the Artiodactyla (cloven feet). 
II. The second hinge-joint in the tarsus of the Artiodactyla. - 
1 Read before the National Academy of Sciences, April, 1881. Abstract. Some 
of the points of this paper have already been discussed in the NATURALIsT (April), 
but the present abstract contains additional matter. 
