105 
Museum Bulletin No. 25. 
Plate XXV. 
A. Symmetrical ripple-mark with small median ridges between much stronger 
angular ridges on Cambrian sandstone, Hammond, N.Y. (Pages 43, 51.) 
B. Symmetrical ripple-mark with sharply angular ridges, Coal Measures. 
Joggins, N.S. (Page 49.) 
