Plate 13 



Fig. 1. Macoma fsrcta. Long BtMcli. Xatuial size. Inteiior right valve. Note 

 large pallial simi.s. 



Fig. 2. Scmrle drrisa Conrad ; l-'lat clam. Fal.se Bay. Natural size. E.xterior 

 of right valve. 



