Raymond. — Correlation of the Ordovician Strata. 



PLATE 6. 



Fig. 1. Cross-bedded limestone at the top of the Wassalem at the type- 

 locaUty. 



Fig. 2. Cliff on the western bank of the Narowa at Narwa, Russia. The 

 Obolus sandstone is seen at the base, and is 11 feet thick. The 

 reentrant at the top of the sandstone indicates the position of the 

 Glauconite sandstone, which is only 4 inches thick. The lower 

 half of the remaining height of the cUff is occupied by the Walchow 

 formation, and the upper half by the Kunda. 



