THE CORAL-KEEF PROBLEM. 51 



fusely among extensive patches of coral sand and fragments. 

 Generally the barren areas much exceed those flourishing with 

 zoophytes, and not infrequently the clusters are scattered like 

 tufts of vegetation in a sandy plain. The growing corals ex- 

 tend up the sloping edge of the reef, nearly to low-tide level. 

 For ten to twenty yards from the margin, the reef is usually 

 very cavernous or pierced with holes or sinuous recesses, a hid- 

 ing place for crabs and shrimps, or a retreat for the Echini', 

 Asterias, sea-anemones, and mollusks. * * * Further in are 

 occasional pools and basins, alive with all that lives in these 

 strange coral seas." 



This description, which is drawn from the islands of the 

 Pacific, is largely applicable to the condition of the Bermudas. 

 Owing to the peculiar submerged condition of the reef I was 

 unable to determine satisfactorily to what extent a breaking 

 surf was favorable or unfavorable to the growth of corals. At 

 the North Rock, the only accessible point of the outer reef, the 

 millepore growth is very profuse, and large masses of Porites 

 may be picked out from below the capping of serpula. The 

 same condition prevails over the Devonshire Flatts, where the 

 surf dashes over a wilderness of atoll-like islets scattered 

 through the lagoon. But this is not necessarily evidence in 

 favor of advantage derived from the surf, since these seemingly 

 more favored patches are the creators of the surf themselves, 

 and they must have risen before assistance from this direction 

 could have been given them. Their existence seems to prove, 

 however, that the action of the surf is no disadvantage, a con- 

 clusion opposed to that which was reached by Bourne from 

 his careful studies of the Diego Garcia Reef.* Along the 

 inner slope of the reef, immediately receding from what might 

 be called the crest, as well as on both slopes of the serpula- 

 capped southern reef, the coral growth appears in unbounded 

 profusion, presenting a perfect maze of millepores, gorgonias, 

 and brain-stones. 



*Proc. Royal Society, XLIII, 1888, pp. 453-55. 



