344 



MARINE BIOTIC COMMUNITIES 



€) 



• 



.^ 





€) 



\ \ 



\ 





"T. 





t> 



Fig. 81. — The Brissopsis-Amphiura ecotone. (After Petersen, 1918.) 



Fig. 82. — The Amphilepis-Pecten biome. (After Petersen, 1918.) 



