530 Dr. W. H. Harvey’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 oiProteacece and of grass trees (^Xanthorrlioea)^ and for the 
paucity of Myrtacece^ Epacridece^ and Leguminosoe (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 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 Avinter 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 Rhodospermew {Laurencice, Hypnees., Acanthophora, &c.); and thickly 
studded with a Caulerpa ((7. loetevirens., 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 
