Vol. XX, pp. 67-70 June 12, 1907 



PROCEEDINGS 



OF THE 



BIOLOGICAL SOCIETY OF WASHINGTON 



ON THE COMPOSITION AND DECOMPOSITION OF 



FPvESH WATER MUSSEL SHELLS WITH^ 



NOTES AND QUERIES. 



BY ROBERT E. C. STEARNS. 



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 l^ecame 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, the 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 l)asins, with the possible ex- 

 ception of A. (Gonidea) angidata, l)elong 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. 



1&-PB0C. Biol. Soc. Wash., Vol. XX, 1907. (C7) 



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