THE BENTHAL 193 



representation of four of them. The index forms of the different facies 

 belong to different groups of animals; lamellibranchs (Fig. 29), sea 

 urchins and starfish (Figs. 30 and 32), crustaceans (Fig. 31), or an- 



n" n "nn n n n nn n nnn n n n 4" n„ n n n „ n n / n >„ Cl 2 y n n n /7 nn n n„ 

 >> ** .* U JJ* n n n n „* ^ "' » *^* V* „ 



n n p°n^so n n q* n " nn ^0 18 n , ° n n -J n n„ . ) n nn 1 „ n n „ 

 "nnn -irn n ^C «"« ^ " T "n n J*" "n » A n % nnn » nn n „„ 



nn nnnn n n n nn 20 n nn n n nPn „r^ ^6/ n „ J - n < 



n n n n n n n n n "\ n n n n ft n .L_ n n n n n n n 





nn,, n' n n \\ n n n n 



•7U nn n n 



\ n „ 



"°j m n Y n n n„n /SS . «n .„ n 9}/ „n n n ^\ 



n 

 " n 8 «n n " n n n n n"" n " n n" ° n ° n ^ n ^) n n rf "n n n 



n 





Fig. 31. — Arrangement of animals on 0.25 sq.m. of sea bottom. Ill, Haploops 

 community at a depth of 27 m. in the Kattegat. The inhabitants are: mollusks: 

 (1) Venus ovata, 1; (2) Cardium jasciatum, 2; (3) Axinus flexuosus, 2; (4) Leda 

 pernula, 1; (5) L. minuta, 1; (6) Lima loscombi, 3; (7) Pecten septemradiatus, 

 2; worms: (8) Aphrodite aculeata, 1; (9) Glycera sp., 1; (10) Eumenia crassa, 

 3; (11) fragment of a maldanid; (12) Pectinoria) auricoma, 1; (13) a terebellid ; 

 (14) Balanoglossus kupfferi, 1; (15) nemertines, 3; ophiurids: (16) Ophioglypha 

 albida, 1; (17) O.robusta, 30; sea urchins: (18) Strongylocentrotus drobachiensis, 

 1; crustaceans: (19) Haploops tubicola (see Fig. 25), 875; (20) Morea lovcni, 1; 

 (21) Ferntca stroemii (on Pecten), 7. After Petersen. 



nelids may fill this role, and they are not necessarily the most abun- 

 dant animals of the community. Some of these communities are rich in 

 variety, up to 20 species, while others are poor (Fig. 29, with 6 species) . 

 In some, one species predominates so much that all others are over- 



