258 



PAPERS FROM THE DEPARTMENT OF MARINE BIOLOGY. 



tory of the Carnegie Institution of Washington, are "hexagonal plates set 

 edgewise. They are optically positive, co = about 1.535, e = about 1.560. These 

 are surely not aragonite, but I can find in the mineral tables nothing cor- 

 responding to them." 1 They require further study. 



Summaries, sample No. 27337. 



I. Numbers of grains of different organisms counted. 



Fine gravel. . . . 

 Coarse sand . . . 

 Medium sand. 



Fine sand 



Very fine sand . 



Total 



39 

 5° 

 11 

 21 

 6 



133 



3i 

 58 

 20 

 20 

 11 



140 



29 



20 

 5 

 9 

 2 



65 



c 



6 



c c 



£2 



M 



o 

 H 



no 

 144 



39 

 S3 

 19 



365 



II. Calculated percentage by weight of different organisms present. 



Fine gravel. . . . 

 Coarse sand. . . 

 Medium sand. , 



Fine sand 



Very fine sand. 



Total 



42.5 



6.3 



13.3 



6.2 



8.4 



•4 



34-6 



15.2 



o-5 

 .1 



0.2 



3 



i-5 



0.4 



6 



97.6 



III. Calculated percentage chemical composition by organisms. 



CaCO,.... 

 MgCO„... 

 CaSO,. . . . 

 CaaPjOs. . . 



38.O 



4.2 



•3 



34-4 

 .2 



15.2 

 .0 



1.0 

 .2 



0.6 



.0 



0.7 

 1 



1-3 



.2 



0.3 

 .1 



0.6 



.0 



92.3 



5-0 



•3 



IV. Calculated percentage chemical composition by size portions. 



Fine gravel 

 Coarse sand . . . 

 Medium sand. , 



Fine sand 



Very fine sand. 



Silt.. 

 Clay. 



Total . 



Per cent 

 present. 



23.6 



37-9 



12.2 



23.2 



• 7 



97.6 



• 7 

 1.2 



99-5 



CaCOj. 



92 



40 



55 



70 



00 



65 



93-7 



MgCOa. 



1. 10 



2.20 



•5° 



LIS 



•OS 



5.00 



Tr. 



Tr. 



S-° 



CaS0 4 . 



0.3 



0.3 



Ca,P 2 0. 



Tr. 

 Tr. 



Tr. 



Silt}\(sample No. 27337). — Contains coccolithophoridae (Pontosphara), 

 minute foraminifera, sponge spicules, etc. 



Clay (sample No. 27337). — -In this clay round coccoliths are abundant; 

 "there are numerous calcite grains and rhombs which appear exactly like 



■Letter of May 9, 1916, from Dr. H. E. Merwin. 



2 See discussion following. 



