VOL. XX, PP. 67-70 JUNE 12, 1907 PROCEEDINGS OF THI: BIOLOGICAL SOCIETY OF WASHINGTON ON THE COMPOSITION AND DECOMPOSITION OF FRESH WATER MUSSEL SHELLS WITH NOTES AND QUERIES. BY ROBERT E. 0. t'TEAILV ; . Thirty years ago, more or less, during my connection with the University of California, there came to hand from some for gotten source, a number of the common West Coast fresh-water mussels Anodonta nuttalliana. I was about to discard the soft parts when it occurred to me it would be better to keep the mussels alive with the possibility of learning something of their habits or behavior. Accordingly they were placed in impro vised aquaria, and the water renewed every day. My time was so closely occupied with various duties that daily renewal of the water was about all the attention they received. In one instance through oversight, the water became stale and the mussels died, so the jar and its contents were placed outside the house. In a short time the soft parts became putrid and soon after the en closing shell also; gradually dissolving like ordinary glue, leav ing nothing but two thin, fragile discoid scales of lime, some thing less in size than a half-dollar, fhe remains of the two valves. The proportion of limy to membraneous or animal matter, was so exceedingly small as to be noteworthy. As all of the so-called species of Anodonta that occur in the Columbia and Sacramento drainage basins, with the possible ex ception of A. (Gonidea) angulata, belong to the group of which the widely distributed A. cygnea is the type, it may fairly be assumed that the proportion of animal to mineral matter in the shells (or valves) as observed in A. nuttalliana, is the same or about the same in the other species here, there and everywhere classed with cygnea. 15 PROC. BIOL. Soc. WASH., VOL. XX, 1907. (07)
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