CONTOUR DIVING 145 



insular shelf. Even to repeat the conditions under which 

 we worked would mean perfect facility for recognizing 

 the change in species of fish and such invertebrates as 

 echinoderms and horny corals; to see and name and note 

 the bottom limits of algae and brain coral; and finally to 

 watch for the end of water-worn and air- worn rocks, and 

 the beginnings of the lava flows of old Bermuda Mountain. 



