Pi^ocEEDiNGS Am. Philos. Soc. Vol. LII. No. 21 1 



Plate XVIII 



Crystalline Rocks of the Interior, Rio Grande do Norte. 



Fig. a. Y-shaped pegmatite dike in biotite-schists near Baixa Verde. Pho- 

 tograph by E. C. Starks, May, 1911. 



Fig. b. Granitic serrotes on the gneissic plain, Rio Grande do Norte. Pho- 

 tographs by G. A. Waring, 1911. 



