152 



HAROLD HEATH AND BLAKE C. WILBUR. 



PLATE I. 

 Explanation of Figures. 



Successive stages in the development of the soldier caste in a young 

 colony of Tcrmopsis nci'adensis. 



FIG. I. Newly hatched young ; head width 0.65 mm. 



FIG. 2. Second instar ; head width 0.96 mm. 



FIG. 3. Third instar; head width i.o mm. 



FIG. 4. Fourth instar; head with 1.73 mm. 



FIG. 5. Fifth instar; head width 2.18 mm. 



FIG. 6. Fully developed soldier; head width 2.6 mm. 



