Plate 17 



Fig. 1. Platijudon cuncclhitiis Conrad. Anaheim Slough. Natural size. E.xterior 

 of right valve. 



Fig. 2. Mya urenaria Linnaeus ; Soft .shell clam. Mouth of Big River. Three- 

 Quarteis natural size. Dorsal view. Note tlie large spoon-shaped pro.iection 

 on tlie left valve for tlie internal ligament. 



Fig. 3. Miia arenaria, same specimen as Fig. 2. Exterior of right valve. 



