530 Dr. "W. H. Haevet's Account of the Marine Botany of 



about twelve miles W. by N. from Fremantle ; and its land Flora is remarkable 

 for the total absence oiProteacea; and of grass trees {Xanthorrha>a), and for the 

 paucity oi Myrtacece, Epacridece^ and Leguminosce (with the exception of Tem- 

 pletonia, and two or three Acacias). It is seven miles long, and about three 

 wide ; it contains several large lakes of salt water, and is indented with many 

 small bays, some of them with sandy beaches, and others rocky. Almost the 

 whole island is surrounded by limestone reefs, at greater or less distances from 

 the shore. The limestone seems of very recent formation, and is of similar 

 character to that at Arthur's Head, and in other localities near Fremantle, al- 

 ready described by several geologists. It is remarkable for very fantastic and 

 diversified forms. The reefs are generally flat-topped, but the surface is very 

 rough, either thickly bristling with sharp points, a few inches high; or broken 

 into miniature mountains and valleys, — strongly recalling to mind the raised 

 map of Switzerland. Other reefs are ridged; the ridges parallel to each other, 

 but variously directed towards the shore. The outer face of the bordering 

 reef is generally very steep, often perpendicular or overhanging ; and frequently 

 it goes down, like a quay wall, into two or three fathoms water. At the N.E. 

 angle of the island, a very remarkable quay-like reef, called the " Natural 

 Jetty," runs out many hundred yards into the sea. Its surface is laid bare, at 

 low-water, of spring tides, which rise and fall from 2 to 3^ feet. Many of the 

 detached reefs are shaped like round tables, or mushrooms, being fixed on a 

 slender central stalk, often only a few feet in diameter; the horizontal ledge, or 

 table, spreading out to many yards on all sides. Sometimes two or three of 

 these tables are joined together by narrow stone bridges; and sometimes large 

 holes, through which you can look down two or three fathoms into the clearest 

 water, are found in the table ; and the swells rise through them, and flow over. 

 I often wondered how these filigree reefs could so long withstand the beating 

 of the waves in winter storms. Almost all of them offer good harvests to the 

 algologist ; and beautiful pictures to any one who can appreciate the loveliness 

 of living vegetable forms. The surfaces of most are well clothed with the 

 smaller Rhodospermece {Laurencice^ Hypiiecc, AcanthopJwra, &c.j; and thickly 

 studded with a Caulerpa (C. Icetevirens, Mont?) with short stems, clothed with 

 brilliant club-shaped leaves, resembling miniature clusters of grapes. At every 

 few yards, deep basin-like hollows, of greater or lesser size, break the surface 



