100 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
The yellowish reef flat is widest at its two extremities ; the coral patches 
appear to be very flourishing, and a few large negro-heads of coral pro- 
truded upon the inner edge of the reef flat. From its diminutive size, 
the whole atoll can be taken in at a glance, and it forms an excellent 
specimen of its kind (Plate 112), with its broad yellow reef flat edged 
on the outside by the white line of breakers separating it from the 
deep blue water, the inner edge passing from yellowish to light green, 
then to light blue, and finally to the darker blue of the central part of 
the lagoon. 
Williamson Reef. 
Plate 19. 
We passed close to Williamson Reef, which is a somewhat rectangular 
reef flat widest at the eastern face. The greater part is dry at low water, 
and encloses a lagoon with thirteen fathoms. The greatest length of the 
reef is a mile and a quarter by nearly a mile at its greatest width. 
Bell Reef. 
Plate 19. 
Bell Reef is separated from the Kimbombo cluster by a channel of 
nearly three quarters of a mile in width. It is irregularly triangular, 
with a reef flat of over half a mile in width. The reef flat of the western 
side is open. The sea breaks heavily on the eastern face, but there is 
little sea on the western face. The greatest depth in the lagoon is 
thirteen fathoms. 
Adolphus Reef, 
Plates 18, 22°, Figs. 16, 17. 
We steamed close to the eastern edge of Adolphus Reef. The outer 
rim is somewhat rectangular in outline, with rounded corners, and 
carries from one to four fathoms of water, enclosing a lagoon twenty 
fathoms in depth. It can be entered from the southwestern angle. 
We could not examine it, as the sea was breaking heavily upon it. We 
could, however, clearly distinguish the patches of corals growing inside 
of the breakers. 
These atolls are excellent examples of the effects of submarine ero- 
sion upon areas of different dimensions, ranging in size from Pitman 
