THE SEA OF JAPAN 



771 



ming among leaves in one case, and those crawling over the bottom and 

 living in the soils among Zostera roots in the other. For the Zostera leaves 

 the following are most characteristic: the Mollusca Lacuna divaricata, 

 Alaba vladivostokensis, Gibbula derjugini, Rissoa sp., Pandalus latirostris, 

 Botryllus sp., and Syngnathus soldatovi. A great variety of Polychaeta Crusta- 

 cea, Mollusca and Echinodermata live in the soil among the stems and 

 under the roots. A Zostera biocoenosis has some features in common with 

 that of Phyllospadix. Some other biocoenoses also inhabit this horizon (0 to 

 10 m) : a fine-grain sand biocoenosis with Mactra sachalinensis, M. sulcataria, 

 Dosinia japonica, Tellina lutea venulosa, Echinarachnius parma, E. griseus, 



V W 



Fig. 383. Composition of bottom biocoenoses in Peter 

 the Great Bay (Derjugin and Somova,) 1 Vermes; 2 

 Echinodermata; 3 Mollusca; 4 Ascidia; 5 Crustacea; 

 6 Varia. I Maldane sarsi+Ophiura sarsi vadicola + 

 Nucula tenuis + Philine japonica; II Turitella fortilirata 

 -\- Amphiodia craterodmeta + Magelona longicornis + Yol- 

 diajohanni+Axinopsis orbiculata; III Venus fluctuosa-\- 

 Ampelisca macrocephala+Haploarthron laeve+Yol- 

 diella derjugini ; IV Pareugyrioides japonica + Venus fluc- 

 tuosa + Yoldiella derjugini + Ampelisca macrocephala ; 

 V Solar iella varicosa+Solariella obscura+Myriotrochus 

 mitzucuri+Stegophiura nodosa +S. brachiactis; VI 

 Heliometra glacialis+Ophiura sarsi+ Verticordia nadina. 



E. mirabilis ; the oyster biocoenosis (O. gigas, O. laperousi, O. posjetica) with 

 many accompanying organisms, among them at times Rapana bezoar; the 

 biocoenosis of Amphiroa cratacea+Mytilus sp. of the type giganteus ; the sea- 

 weed biocoenosis Sargassum, Cystophyllum, Coccophora, Rhodomela and 

 others on the cliff sectors washed by the surf; the biocoenosis Balanoglossus 

 proterogonius-\- Tellina incongrua-\-Lebidoplax variabilis on sectors heavily 

 covered with silt at a depth of 3 to 5 m, and a series of others. Somewhat 

 below these (12 to 50 m) lies the horizon of Laminaria (L. saccharina, L. 



