Proceedings Am. Philos. Soc. Vol. Lll. No. 21 1 



Plate XVI 



Rio Gkamhc do Xoute Rkefs. 



Figs, a and h. Looking north along an organic reef off the coast from 

 Piringy. Photographs by E. Leib, May, 191 1. 



Fig. c. Looking along the sandstone reef at Natal toward the fort, showing 

 etched and fallen blocks. Photograph by G. A. Waring, Nov., 191 1. 



