Raymonp.— Correlation of the Ordovician Strata. 
PLATE 6. 
Fig. 1. Cross-bedded limestone at the top of the Wassalem at the type- 
locality. 
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 
reéntrant 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 cliff is occupied by the Walchow 
formation, and the upper half by the Kunda. 
