876 



BIEDEL 



[CHAP. 33 



"the distribution of the dead shells of the pelagic Foraminifera on the floor of 

 the ocean corresponds exactly with the distribution of the living specimens at 

 the surface of the sea . . . ; the distribution of the dead shells on the bottom does 

 not appear to be much if any wider than that of the hving specimens at the 

 surface, and this shows that the dead shells must reach the bottom a very short 

 time after the death of the organisms". Schott (1935) examined this matter in 

 the equatorial Atlantic and found Murray's statement to be generally correct if 

 allowance is made for dissolution of some of the more delicate tests. Semina and 



l\ 



200ti . 



Fig. 9. Sponge spicules from an Atlantic pelagic sediment. (Lament core A167-44, 25° 40'N, 

 77'' 21'W, 5-10 cm below sediment surface.) 



Jouse (1959) found a correspondence between diatom biocoenoses and thanato- 

 coenoses in the western part of the Bering Sea, again allowing for impoverish- 

 ment of the thanatocoenoses due to selective dissolution of the dehcate frustules 

 of some species. 



A less direct approach is to chart distributions of species and assemblages in 

 Recent sediments and compare them with the pattern of overlying water 

 masses. If the pattern of faunal assemblages in Recent sediments mirrors that 

 of the more or less discrete water masses above, it appears permissible to 

 conclude that the assemblages of living organisms represented are related to 

 those water masses, and that there has been little lateral displacement of the 

 skeletons during their descent to the sea floor. Kanaya {in litt.) is engaged in a 

 study of the diatoms in Quaternary sediment samples from the Pacific floor, 

 and has been able tentatively to distinguish five distinct diatom assemblages in 



