Explanation of Plate I. 
Figure 1. 
« 2 . 
3. 
4. 
Figure 5. 
6 . 
7. 
8 . 
9. 
Leptaena sinuosus n.sp. 
Natural cast of interior of ventral valve of type specimen x 2 
Natural cast of exterior of ventral valve x 2. Figures 1 and 2 rep- 
resent exterior and interior views of the same specimen of a 
ventral valve; Chemahawin, Man. 
Natural cast of exterior of brachial valve x 2. Chemahawin, Man. 
Natural cast of interior of dorsal valve x 2. Figures 3 and 4 rep- 
resent exterior and interior casts of a single shell. 
Leptaena parvula n.sp. 
Natural cast of interior of ventral valve of type specimen x 2. 
West of Gypsumville, Man., 8 miles. 
Gutta-percha cast of exterior of ventral valve x 2. 
Natural cast of interior of dorsal valve x 2. Chemahawin, Man. 
Natural cast of exterior of brachial valve. Chemahawin, Man. 
Gutta-percha cast of interior of brachial valve x 2. West of Gypsum- 
ville, Man., 8 miles. 
