232 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



erosion or to the solvent action of the sea, differing in no way from those 

 made along the north and south shores of the islands. Along its shores 

 there are numerous ledges running out from or parallel with them, ex- 

 tending between the small rocky promontories, which if cut off would 

 form a series of patches close to shore similar to those which extend from 

 the north shore inside of the banks towards the outer ledge flats and 

 upon them. Gorgonians, corals, and other growths, have settled upon 

 the ledges since the time when they and the saddles have sunk or have 

 been ei'oded to their present level, giving the sea access into the interior 

 of the various sounds so characteristic of the Bermudas. This is admi- 

 rably shown by the cutting of the sea into St. George Harbor, so as to 

 give access to it both from the outer and inner waters of the bank. 

 These passages are narrow, so that corals do not get a sufficient supply 

 of fresh water, and hence are far less common than on the shelves of Cas- 

 tle Harbor, which is freely connected with the sea on its southern expos- 

 ure. In Harrington Sound the connection with the lagoon is still less 

 open, a narrow cut on the north being the only opening through which 

 the inner waters of the bank gain admission to it. Castle Harbor in the 

 same way is connected freely with the sea on the south, and but slightly 

 with the inner waters of the bank, through the same opening which con- 

 nects them with St. George Harbor. 



A narrow cut separates Somerset Island, which forms the western 

 boundary of Great Sound, from the main island. This sweeps round to 

 the eastward and forms the southern flank of Port Royal Bay, which is 

 separated from Great Sound by the line of islands extending outward 

 from Tucker to Darrel Island (Plate II.). 



The depth of water in the sounds is very considerable, not only in the 

 sounds themselves, but also in the inner waters of the reef, which have 

 been called lagoons, but are hardly such in the sense in which that term 

 is understood. It would greatly conduce to accuracy to call the inner 

 basins of deep water — surrounded on one side by the outer ledges of 

 the reef, and on the other either by the connecting patches of ledges or 

 by the islands in part — sounds also, for such they undoubtedly are, and 

 were sounds similar to those now existing and known as Great Sound, 

 Port Royal Bay, Hamilton Bay, St. George Harbor, Castle Harbor, and 

 Harrington Sound. 



In Great Sound we find from ten to eleven fathoms. In Harrington 

 Sound as much as twelve fathoms is found in several spots. In the outer 

 sounds we do not as a general rule find so great depths. What we may 

 call the Brackish Pond and Bailey Flats Sound has a general depth of 



