1 12 PROCEEDINGS OF THE AMERICAN ACADEMY. 



4. Two " stages " appear to be represented by the individuals meas- 

 ured. Many of the curves are compound, and it is probable that in these 

 one mode represents those individuals which have recently molted, the 

 other those which are almost ready for the process. 



5. All the measurements are larger on the side of the great chela. 



6. The results of this study in variation seem to indicate that right- 

 and left-handednese is not directly due to heredity, but is caused by 

 certain Blight variations which give one side of the body an advantage 

 over the other. 



Bibliography. 



Bateson. W. 



'94. Materials for the Study of Variation treated with special Regard 

 to Discontinuity in the Origin of Species. London and New 

 York, Macmillan iN Company. 608 pp. 

 Davenport. C. B. 



'99. The Importance of Establishing Specific Place-Modes. Science, 

 M.S., Vol. 9, No. 220, pp. 415-110. 

 Davenport. C. B. 



'99v Statistical Methods with special Reference to Biological Variation. 

 59 pp., h) tables, and 28 figs. New York, John Wiley & Sons. 

 Weldon. W. F. R. 



'93. On Certain Correlated Variations in Carcinus maenas. Proc. Roy. 

 London, Vol. 51, pp. 318-329. 



