108 



Table VII. 

 Analysis of numbers of individuals and species of living and dead in- 

 vertebrates from five successive Petersen Grab samples at Station P51, 

 depth 16 meters, fine sand bottom. 



Species 



Samples 



C. 



Oliva incrassata 



Nassarius pagodus 



Architectonica placentalis 



Natica caneloenensis 



Terebra malonei 



Phos articulatus 



Eulima varians 



Balchis, sp 



Pyramidella conica 



Terebra variegata 



Polinices intemerata 



Philine, sp 



Nuculana, sp 



Chione mariae 



Corbula, sp 



Tellina felix 



Lucina approximata 



Pilar concinnus 



Pandora, sp. (juv.) 



Periploma, sp. (juv.) 



Chione, sp. (juv.) 



Tagelus politus 



Anadara perlabiata 



Corbula luteola 



Cyclinella, sp 



polychaetes 



Total species living 



Total species dead 



Total individuals, living. 

 Total individuals, dead . 



/ = living 

 1 = dead 



5 + 



/ 

 1 

 1 



6 

 2 

 1 

 /,3 

 / 

 7 

 / 



5 + 



5 + 



6 



6 



10 



14 



2, 10 



/,3 



5 + 



4 



3 



9 



20 



5 + 



levelling off. On the other hand, both curves from boreal waters level off 

 after a few samples, and virtually no new species are added after the 

 fourth or fifth sample. Each new Gulf of California sample produces 

 nearly a whole new set of species. 



