1918] Packard: Quantitative Analysis of Molluscan Fauna 315 
It is probable that the tide flats of San Francisco Bay are best 
adapted to Mya arenaria, although certain beaches are perhaps more 
suitable to Paphia staminea or other local species not as well known 
to the public. Those adapted to the exposed ocean beach include 
Siliqua nuttalli, Mytilus californianus, Solen sicarius, Saxidomus nut- 
talli, Schizothaerus nuttalli, and Cardium corbis. 
Such an industry as clam farming would not succeed without 
private control of the tide flats. This has been demonstrated along 
the Atlantic Coast, where suitable acreage is either sold or leased to 
the individuals. A law giving the exclusive rights to a certain pro- 
portion of the tidal areas ought not to be enacted until an investi- 
gation of the clam beds of the state has been made. Such an investi- 
gation would include a survey of the tide lands from the standpoint 
of tidal bottom, naturally productive or barren beds, their present 
fauna, their position as regards tidal currents, and their position as 
regards possible contamination from sewage. From such data as these 
it would be possible to determine what tracts were suitable for clam 
farming by the individual and what tracts should be retained as public 
property. The clamming industry would further profit by the de- 
termination of those localities where the natural set is heavy. Such 
localities should perhaps remain as public property in order that the 
young clams might there be obtained with which to transplant the 
barren areas. Other problems of interest to the clam farmer that 
such a survey would solve are the period of spawning, the local rate 
of growth of the different clams, and the season of maximum growth. 
These would enable the clammer to determine when to transplant the 
young and what sizes to use. Such an investigation might well include 
the market conditions, and especially the possibilities of canning the 
product. It might also be found that the demand for such sea food 
could be materially increased by a well organized advertising cam- 
paign. 
The possibility of locating shell deposits within San Francisco Bay 
which might be dredged for their lime content has led to the prepar- 
ation of table 5. 
Eleven out of seventy-nine tubular bottom samples examined quan- 
titatively by Sumner ef al. show a lime content greater than 10 per 
cent. These samples were obtained from four regions, from the ex- 
treme upper to the lower end of the bay. One small and economically 
unimportant area occurs in Carquinez Strait, at station D 5816 A. 
Although the bottom sample shows a high percentage of lime, the 
