485 A. E. Verrill—The Bermuda Islands. 
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The great star-coral, with star-shaped calicles about one-quarter or 
one-third of an inch across ( Orbicella cavernosa), forms large solid 
hemispheres, but it only lives on the outer reefs. The smaller kind 
(O. annularis), with calicles about one-eight of an inch across, is also 
found chiefly on the outer reefs, but is more common. The Sider- 
astrea radians, which has crowded, shallow, confluent stars, about 
one-eighth of an inch across, is very abundant both in shallow water 
and on the reefs. It grows in solid, heavy, rounded masses up to a 
foot or more across. Porites astreoides forms irregular rounded 
and tubercular masses, up to two feet in diameter, covered with 
minute stars, about =1, of an inch or less in diameter. It is usually 
dark yellowish brown when living. (See Part V.) 
At the western end of the group the reefs cover a very extensive 
semicircular area, extending 7 to 9 miles from land, with a perfect 
labyrinth of broken and detached reefs, but more continuous toward 
their outer margins. his reef area is larger than all the dry land. 
Figure 28.—Wreck Hill, as seen from the Sea, bearing N. 34 Hast; after 
Findlay. 
Among the most dangerous of these reefs are the Chub Heads, 
which lie 9 miles from the shore at Wreck Hill ; Long Bar, of which 
the south part is 6 miles W.S.W. from Gibb’s Hill Light; and 
Southwest Breaker, on which the sea always breaks, and which lies 
15 miles from the shore, and about south from Wreck Hill, which is 
a rather conical high hill, standing detached from the other hills, at 
the extreme western end of the main island. When seen from the 
sea it appears dark colored. From the southwest it appears flat- 
tened at the top, but from the south it is conical. It is usually the 
first land made in approaching the islands from the westward. (Fig. 
28.) ‘The modern sand-dunes in the region of Elbow Bay, East of 
Gibb’s Hill Light, are conspicuous at sea, from a long distance, by 
reason of their white color, and are called the Sand Hills. 
