YERKES. 



VARIATION IN THE FIDDLER CRAB. 



431 



Polygon No. 6R. 



PoLYGOv No. 6L. 



6. Carpopodite of great chela. Here we meet an exception in the 

 matter of modal frequency, for the Lefts' mode contains more individuals 

 than that of the Rights. No. GR and 6L are otherwise similar. In 

 comparison with the meropodite the carpopodite is much more variable. 



Bateson ('94, p. 79), in his book on meristic variations, states that 

 terminal members of a series are likely to be most variable. " In such 

 cases as that of the last rib of I\Ian, and several other animals, the wis- 

 dom teeth of Man, etc., it is (juite true that in the terminal member 

 Variation is more noticeable than it is in the other members." But such 

 series as those of teeth and ribs, in which there is repetition of similar 

 organs, are so different from the linear series of joints with which wt; 

 are dealing, as to make inferences from one to the other unwarrantable. 



