20 
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Explanation of Plate IV. 1 
Figure 1. Pinna curvimarginata McLearn n.sp. Bight valve. Geol. Surv., Can., Mus. No. 5397, 
holotype. 
2. Unio dowlingi McLearn n.sp. Bight and left valves. Geol. Surv., Can., Mus. No. 5400, 
holotype. 
3. Trigonia albertaensis McLearn n.sp. Left valve. Geol. Surv., Can., Mus. No. 5401, 
holotype. 
4. The same. Cast of right valve. Geol. Surv., Can., Mus. No. 5402, paratype. 
X A11 illustrations are natural size. 
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