262 



LEON J. COLE. 



I 



cit., Fig. 154) of the leg of an insect, and most of the cases fit in 

 with these expectations very well. 



Adapting to the lobster Bateson's diagram for the theoretical 

 positions of the extra parts when they arise from the ventro- 

 posterior {v. p.) side of the normal appendage, as in the present 

 case, we have the relations as shown by the complete outlines 



Fig. 7. Diagram illustrating (full outlines) Bateson's "rules of secondary 

 symmetry" as applied to a left lobster chela with double extra claws arising from 

 the ventro-posterior side. The dotted outlines show the positions these parts 

 would assume if each claw were rotated anteriorly, independent of the others, 

 through an arc of 80°. 



in Fig. 7, no allowance being made for torsion. But we have 

 seen {p. 259) that the normal lobster claw becomes rotated 

 anteriorly through an arc of approximately 80°. If we now 

 rotate independently toward its anterior side each of the diagram- 

 matic claws in Fig. 7 through an arc of 80°, we arrive at the posi- 



