ZOOLOGY OF THE BERMUDAS. 99 



served between the marginal growth and that which extends 

 gradually backward from the margin into deep water. In- 

 deed, as far as the brain-corals themselves are concerned, it 

 appeared to me that their largest masses were to be found 

 some distance within the bounding reef, and consequently be- 

 yond the breaking action of the surf. This condition is again 

 shown in the comparatively quiet and sheltered waters of Cas- 

 tle Harbor, where portions of the platform-bottom may be said 

 to constitute one almost connected mosaic of huge Diplorias. 

 In so far, therefore, the Bermudas differ from the greater num- 

 ber of coral islands, in which, as is commonly stated, there is 

 a marked deficiency in the coral growth within the bounding 

 area, and an equally marked luxuriance on the crest and outer 

 slope of the reef. 



In most places the largest corals do not come nearer than a 

 foot or two feet of the surface of the water, the massive brain- 

 corals rarely appearing in water of less depth than five or six 

 feet. But in the shallows off the North Rock we found Porites 

 astraeoidcs almost at the surface in low water, and just off 

 the entrance to Harrington Sound, on the north shore, Sideras- 

 trsta galaxea was covered by only about two inches of water. 

 The borders of Harrington Sound are largely overgrown with 

 species of Isophyllia, which likewise approach to within a short 

 distance of the surface. In the greater depths of the Sound we 

 found only Oculina, down to ten fathoms, the dredge-net being 

 frequently caught and reversed by their ramose stems ; beyond 

 ten fathoms the dredge usually came up empty. 



The following species were obtained by us : 



Mycedium fragile, Dana. 



Two specimens. North Rock ? 



Oculina diffusa, Lamk. 



Harrington Sound. 



Oculina varicosa, Lesueur. 



Harrington Sound. 



Oculina pallens, Ehrenberg. 



Harrington Sound. 



