550 The American Naturalist. [July, 
will mark the evolution of the race. In the earliest ungulates 
the carpals and tarsals are disposed, as in man, directly above 
each other, with serial joints, as in A; in the course of 
evolution all these joints became interlocking, as in B, thus 
producing an alternation of joints and surfaces similar to 
those which give strength to masonry. In studying these 
facts Cope’ reached a certain theory as to the motion of the 
foot and leg in locomotion. In trying to apply this, I found 
it could not be harmonized with all the facts, and I worked 
out an entirely different theory.” This I found subsequently 
coincided exactly with the results previously obtained by 
Muybridge, by the aid of instantaneous photographs, and 
summarized by Professor Harrison Allen, of the University of 
Pennsylvania.’ 
Radius Ulna Radius 
Index Med? Ann? 
peg “ide of te 
1 by SI Q! e cle 
middle toe, IIT. "ena of toes would pier Rang oF E All Joints “broken aA 
use separation of the carpals. radius, the bones receiving greatest impact 
in in walking. Lateral toes, V., degen- 
The monodactylism of the horse was attained by the 
atrophy of the lateral toes, and concentration of the major 
axis of body-weight and strain upon the middle finger and 
toe. Man is also tending toward monodactylism in the foot 
1AMERICAN NATURALIST, 1887, p. 986. 
*See Trans. of American Philosophical Society, p. 561. Philadelphia, 1889. 
The Muybridge Work at the University of Pennsylvania. Philadelphia, 1888. 
