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 calif or nianus, Solen sicarius, Saxidonius nut- 

 talli, Schizothaerus nuttalli, and Carclium corhis. 



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 materiallj^ 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 et 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 



