EXPLANATION OF PLATE III. 



Spongilla alba, Carter. 



A rock at the edge of the Chilka Lake partly covered by the sponge. 



The photograph was taken in November after the level of the lake had sunk about 5 feet, leaving 

 the sponge dry. The rock was 2 ft. 11 in. in width and was covered with a somewhat sparse growth of 

 filamentous alga. The sponge had grown over this alga on the lower part of the rock and the appa- 

 rent brauches on its surface were actually thin incrustations of the filaments. 



