78 



GRANT 





'**-'*t^^. 



10 KM 



I I I I I I I I I I I 



\ 



West 

 Spit 



12 \ VAN 



RIGILI 19 

 20 



10 



•• CHINIMI 



Southwest 

 Passage 



15. 



». ♦ MUTI 



16-18. i '^C^^. 



\ 13 



GRINEM 



^ia 



IGURIN 



14 



c- 



7 



PARRY ^-sy 



ENEWETAK 



South Channel 



Fig. 1 Map of Enewetak showing where brachiopods were collected. Numbers are last digits of USNM locality numbers 

 32007-22. 



coral frond at 5 m. The abundance and diversity of bra- 

 chiopods increase with depth and with increased darkness 

 in small caves and recesses in the reef. On the seaward 

 side of Biken Island, one piece of coral-cum-sponge con- 

 tained a density of Thecidellina congregata that by extrapo- 

 lation amounts to 7000/m^, and another has 40 individu- 

 als on a surface 7 X 17 cm, amounting to about 

 3400/m^ (Figs. 6 through 8). These densities compare to 



those found by Jackson et al. (1971) at Jamaica and 

 Curasao where densities of 5000 to 10,000/m^ were 

 encountered. These figures may appear to exaggerate the 

 density of brachiopods on these reefs, because the com- 

 mon impression is that brachiopods are rare. Most divers 

 do not encounter brachiopods, however, because they do 

 not search for them deliberately, and brachiopods are 

 essentially invisible under water. In addition, the distribu- 



