432 



PROCEEDINGS OP THE AMERICAN ACADEMY. 



Bateson does mention (p. 63) substantive variation in the joints of the 

 leg of the cockroach (Blatta americana), but only in its relation to the 

 number of joints, no light being thrown upon our problem. 



In case of the series of joints of the crab leg it would seem probable 

 that the distal would be the most variable, since they are most likely to 

 be modified by the use of the leg. 



For convenience of comparation the Coefficients of Variablity of 

 the measurements taken on the chelar joints are here repeated (see 

 Table II.). 



Meropodite of great chela, 

 Carpopodite of great chela, 

 Propodite of great chela, 

 Meropodite of small chela, 

 Carpopodite of small chela, 

 Propodite of small chela, 



Only for the great chela of the Rights is there a constant increase in 

 variability from the proximal to the distal joint. In every case, how- 

 ever, the carpopodite is much more variable than the meropodite. 



Polygon No. 7R. 



