212 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



at so many points, not only of the outer reef ledges, but on the flats inter- 

 vening between them and the Lagoou (Plate XVIII.). Between these 

 patches separated by deep water, and plainly seen by its discoloration, it 

 is comparatively easy to find one's way when the water on the banks 

 is not rendered milky by winds stirring up the bottom. 



Lagoons similar to those between the reef and the islands are Great 

 Sound, Port Royal Bay, Hamilton Harbor, Harrington or Little Sound, 

 St. George Harbor, and Castle Harbor. These sounds, as the inner 

 lagoons are called, differ from similar sinks in the outer lagoon by being 

 bounded in part or wholly by land, while the sounds in the outer lagoon 

 are more or less indistinctly limited by flats formed of "coral head" 

 patches (Plate I.). 



Harrington Sound is connected with the outer lagoon by a narrow 

 channel, the Flats Inlet ; it is, in fact, in the condition of many of the 

 smaller bays on the south shore, where the sea has only comparatively 

 lately encroached upon the interior sinks. I refer to such bays as 

 Sinky, Hungry (Plate XV.), Devon, and the like. In the case of Little 

 Sound, the opening at Flats Iulet broke through the ridge separating 

 the outer lagoon from an extensive sink, the smaller elevations of which 

 have entirely disappeared, with the exception of a few islands and shoal 

 patches. Castle Harbor and St. George Harbor were probably similar 

 sinks, the outlines of which are still indicated by the line of islands 

 protecting in part the southern face of Castle Harbor, while the out- 

 line of the narrow sink forming St. George Harbor is shown by the 

 islands which separate it from the Narrows, and by St. David and 

 Long Bird Islands, which are the remnants of the ridge dividing St. 

 George from Castle Harbor. But both these ridges are now broken 

 through, so that Castle Harbor connects with St. George Harbor and on 

 the north with the lagoon forming Murray Anchorage. 



The aeolian hills extending eastward from the northern entrance to St. 

 George Harbor are most characteristic, and the saddles separating them 

 are of varied elevations, and show how readily the sea could, after a 

 very limited subsidence, find its way into sounds like Castle and St. 

 George Harbors at a time when they probably appeared much like the 

 nearly closed Harrington Sound (Plate V.). 



As Professor Heilprin has stated, it is merely a question of time when 

 Harrington Sound will be more of an open bay than of a land-locked 

 lagoon, presenting in time the appearance of Castle Harbor, and finally 

 perhaps that of Great Sound. 



An examination of the chart (Plate I.) reveals faintly the position of 



