AGASSIZ • BAHAMAS. 35 



hills become lower as we proceed south, and then rise again to form the 

 rectangular shank of Cat Island exteudiug from Hawk's Nest to Colum- 

 bus Point. The highest hills of this part of the island are to the 

 northwest of Columbus Point, on the western shore, near Fernandez 

 Cay. There are a few isolated patches of reefs on the northeastern ex- 

 tremity of Cat Island, but none along the narrow bank formed by the 

 100 fathom line, extending from there to Columbus Point. To the east- 

 ward of Hawk's Nest there are patches and stretches of coral heads, 

 forming an excellent reef harbor, Port Howe, between the Devil's 

 Point and the Bluff. 



Nassau to Harvey Cay. 



Plate I. ; Plate X. Fig. 2 ; Plate XXXVI. 



Passing out from Nassau to the eastward, Potter Cay divides the 

 main channel into two parts, one of which is quite shallow. The Eeolian 

 character of the low hills forming the base of the promontory at the ex- 

 tremity of which stands Fort Montague is well marked, and as we steam 

 out we can see their continuation to East Point. On the other side of 

 the channel we pass a series of low islands, 1 Hog, Salt Cay, and Athol, 

 on the last of which stands the lighthouse. Their southern face is formed 

 of low vertical cliffs ; the vegetation upon these islands is scanty. 



Dredging occasionally beyond the eastern channel, we brought up 

 nothing except algae and corallines ; we passed a few patches of coral 

 heads and of Gorgonians, generally opposite to openings between outlving 

 islands which give a freer access to the water from Providence Channel. 

 Our course lay southeast from the Porgee Rocks, and for a considerable 

 distance we passed over a bottom nearly barren of animal and vegetable 

 life ; it consisted mainly of clean sand, with here and there a coral patch 

 or a cluster of Gorgonians ; but the farther south we steamed on the 



1 It seems to me that the explanation given by Dr. Northrop (Trans. New York 

 Acad, of Sci., Oct. 13, 1890) regarding the formation of the cays north of Nassau 

 Harbor is not the correct one. They owe their existence, not to the coral sand which 

 has been thrown up from (he outlying coral reef, but to the denudation and erosion 

 of an outer line of aeolian hills parallel to the Nassau range which forms their base- 

 ment. It is true that upon their sea face coral sand has been heaped up between 

 the headlands of the aeolian hills composing the cays, and sometimes blown to a 

 considerable height to form broad and high beaches, as on the sea face of Hog 

 Island, but the aeolian rock underlying them crops out in all directions, especially 

 on the south side of the cays. 



