428 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



Lefts respectively. No. 3R differs from 3L in having greater modal fre« 

 quency and more classes ; it differs from 4L by much greater modal 

 frequency. As compared with the left margin the right is somewhat 

 less variable. For both Rights and Lefts the margin on the side of 



Polygon No. 3R. 



Polygon No. 3L. 



the small chela is 5% shorter than the other. In the case of the Rights, 

 8.400 (Left) ^ 8.842 (Right) = .9500, i. e. Left is 95% of Right. And 

 for the Lefts 8.285 (Right) -f- 8.716 (Left) = .9505, i. e. Right is 95+ % 

 of Left. All dimensions are considerably larger on the side of the 

 great chela, a fact which will be discussed later in connection with the 

 problem of right- and left-liandedness. 



