97 
Museum Bulletin No. 25. Plate XXI. 
A. Symmetrical ripple-mark formed by wave action, under 4 inches of 
water, and photographed through water, Aylmer, Que. 
B. Plaster cast of symmetrical ripple-mark with rounded ridges, formed 
by wave action, under 4 inches of water, Aylmer, Que. 
C. Plaster cast of symmetrical ripple-mark with angular ridges, from cast 
taken at a depth of 6 feet, lake Ontario near Wellington. 
(Pages 23, 24.) 
