AGASSIZ: BAHAMAS. 93 



with patches of the common West Indian Gorgonians. The corals on 

 the bank exist in irregular patches, and do not extend any distance 

 eastward. They flourish along a narrow belt on the edge of the bank, 

 between three to six and fifteen or sixteen fathoms. 



On the bank side of Fortune Island the slope of the hills runs insen- 

 sibly into shallow water ; but, steaming on the western face, the shores 

 all the way from the South Spit of Fortune to its northern extremity 

 are flanked by low seolian cliffs interrupted by steep coral sand beaches. 

 Above the low cliffs extends for a considerable distance a line of an- 

 gular rocks thrown up above high-water mark by an unusual swell or 

 by hurricanes. 



The lagoon which extends south from the settlement nearly to the 

 southern end of Fortune Island is separated from the sea by a high 

 steep coral sand beach (Plate X. Fig. 4). The beach becomes gradu- 

 ally much lower north of the settlement ; it extends all the way 

 to the northern extremity of Fortune Island, and is again seen on 

 Crooked Island, being nearly unbroken along the whole shore line as 

 far as Portland Harbor at the northern end of the island. Crooked 

 Island is also built of aeolian hills with gentle slopes to the west except 

 near its northern spit, whore the shores consist of low vertical cliffs. 



From Bird Eock lighthouse the beautiful sweep of a coral reef con- 

 necting it with Crooked Island forms a fine bay sheltered from the north- 

 east trades, the green waters of which stand out in marked contrast with 

 the dark blue of the deep water off the bank, while the white wall of 

 breakers marks the dividing line between it and the deep water to the 

 east. 



If Columbus visited Bird Rock, or Cape Beautiful, as some writers call 

 the western end of Crooked Island, he could not have failed to notice 

 a physical phenomenon so strange to him as that of a coral reef forming 

 a bay well protected from the prevailing winds, nor could such a sharp 

 observer have failed to describe at length, or to note at least, this pecu- 

 liar feature of the sea. 



To the westward of Castle Island is the Mira por vos Bank, with 

 soundings near the edge of from five to nine fathoms. It is pear- 

 shaped, with a cluster of low barren rocky cays, the highest of which 

 is but thirty feet. At the north end they are connected by a reef; and 

 there are several disconnected patches of corals, with three fathoms of 

 water over them. 



Two other small banks rise in the Crooked Island passage. Diana 

 Bank, twenty miles to the west of Fortune Island, is about four miles 



