Before the present investigation, there were only 20 species of diatoms recorded fromthe continental shelf of the East China Sea. All the surface sediments were collected bythe First and Second Institutes of Oceanography, National Bureau of Oceanography fromOct. to Nov. of 1977. Three sections including 26 stations were selected in almost equaldistances from each other at random, from a range of 28°30′N to 32°30′N, and fromthe coastal region to 129°E. Their exact positions are plotted in Fig. 1. About 50 grams of samples from each station were taken, and treated with diluteHCl, Conc. H_2SO_4 and then CdI_2 (sp.g. 2.4), to separate the diatoms from the se- Before the present investigation, there were only 20 species of diatoms recorded from the continental shelf of the East China Sea. All the surface sediments were collected by the First and Second Institutes of Oceanography, National Bureau of Oceanography from Oct. to Nov. of 1977. Three sections including 26 stations were selected in almost equal distance from each other at random, from a range of 28 ° 30’N to 32 ° 30’N, and from the coastal region to 129 ° E. Their exact positions are plotted in Fig. 50 grams of samples from each station were taken, and treated with dilute HCl, Conc. H 2 SO 4 and then CdI 2 (sp.g. 2.4), to separate the diatoms from the se-