the canadian field naturalist natural history 68 the canadian field naturalist vol xxxv canadian sphaeriidae by the hon mr justice latchford confiiiurd fom vol xxxfv p 71 21 muscllirm secriuypriiue this gtpeeies resembles t uncatuin in the alrtipt iiess of the posterior margin hut is a smaller shed its anterior margin is shorter and more rounded and the lines of growth are deeper and more distinct tie valves are thicker less glossy and paler within and without it occurs on a muddy bot tom in st louis dam inside the viaduct and probably outside it and in rg3ddt.jpg from xxxfv View Photo