194 



MARINE ANIMALS 



shadowed, for example, Amphiura filiformis (Fig. 30), and finally 

 Haploops with 875 specimens to 64 of the other species combined (Fig. 

 31). In others, a number of species are approximately equal in abun- 

 dance. These facies of the plantless sea bottom bear some relation to 



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Fig. 32. — Arrangement of animals on 0.25 sq.m. of sea bottom. IV, Brissopsis- 

 Sarsii community, at a depth of 186 m., in the Skagerrak. The inhabitants are: 

 mollusks: (1) Abra nitida, 179; (2) Cardium minimum, 11; (3) Axinus flexuosus, 

 20; (4) Portlandia lucida, 1; (5) Leda pernula, 17; (6) L. mitwta, 1; (7) Nucula 

 tenuis, 14; annelids: (8) Aricia norvegica, 9; (9) Artacama proboscidea, 8; (10) 

 Melinna cristata, 8; (11) Pectinaria auricoma, 1; (12) Eumenia crassa, 1; (13) 

 Myriochele heeri, countless; ophiurids: (14) Amphiura elegans, 2; (15) 

 Ophioglypha sarsii, 5; sea urchins: (16) Brissopsis lyrifera, 9. After Petersen. 



the distribution of the fishes, certain fishes being found principally in 

 or over similar biocoenoses, although never as index forms and always 

 free to move over other types of bottom. These facies established by 

 Petersen have a wider application than to the Danish waters as shown 

 by the application of Petersen's methods to the study of the animal 



