1918] Packard: Quantitative Analysis of Molluscan Fauna 



307 



TABLE 2 



A Eecord of the Most Productive Quantitative Haul, Station D 5833 



Number Total Modal 



of living number of lengths 



individuals individuals in mm. 



Cardium corbis 29 24 



Macoma balthica 128 127 15 



Macoina inquinata 7 38 



Macoma nasuta 20 55 



Mya arenaria 1 22 



Mya California —- 2 7 11 



Mytilus edulis 2 33 



Ostrea lurida many 



Paphia staminea 1 3 10 



Sehizothaerus nuttalli fragm. 



Zirfaea gabbi fragm. 



Crepidula nivea fragm. 



Epitonium hindsi 128 128 3 



Epitoninm sawinae 1 



Nassa fossata 1 22 



Thais lamellosa 14 13 



It is of interest to note the average size of a few of the prevalent 

 species. Such data are tabulated below. 



The averages as given above are rather low, due in part to the 

 relatively large numbers of very young individuals. These figures, 

 however, combined with those given elsewhere in this paper, make it 

 possible to picture the molluscan life of a typical unit area, besides 

 giving the approximate numbers and dimensions of the individuals 

 living within such an area. It is also possible to estimate roughly 

 the amount of organic matter represented by the mollusks, after once 

 having established the average number and size of the individuals 

 per unit area, and the ratio of the organic to that of the inorganic 

 matter for each species. 



A picture of the molluscan life of an average unit area, such as 

 would be covered by the jaws of the orange-peel bucket dredge (7.8 

 square feet), may be obtained from a consideration of the data pre- 

 sented above. 



