EXPLANATION OF PLATE 53 



All figures approximately natural size 



Fig. 1. Amiantis dalli, n. sp. Left valve. Longitude, 72 mm. 



Fig. 2. Amiantis dalli, n. sp. Anterior view of same specimen as figure 1. 



Fig. 3. Amiantis dalli, n. sp. Hinge plate of left valve. This specimen 

 shown also on plate 50, figure 2. 



Fig. 4. Amiantis dalli, n. sp. Hinge plate of right valve. 



Fig. 5. Pitaria stalderi, n. sp. Hinge plate of left valve. Longitude, 59 mm. 



Fig. 6. Pitaria stalderi, n. sp. Eight valve. Longitude, 64 mm. 



[5361 



