Coral-eating
fish--Coral formations--Lagoon islands or atolls--Depth at
which reef-building corals can live--Vast areas interspersed
with low coral islands--Subsidence of their foundations--
Barrier-reefs--Fringing-reefs--Conversion of fringing-reefs
into barrier-reefs, and into atolls--Evidence of changes in
level--Breaches in barrier-reefs--Maldiva atolls, their
peculiar structure--Dead and submerged reefs--Areas of
subsidence and elevation--Distribution of volcanoes--
Subsidence slow and vast in amount.

CHAPTER XXI.

Mauritius, beautiful appearance of--Great crateriform ring of
mountains--Hindoos--St. Helena--History of the changes in
the vegetation--Cause of the extinction of land-shells--
Ascension--Variation in the imported rats--Volcanic bombs--
Beds of infusoria--Bahia, Brazil--Splendour of tropical
scenery--Pernambuco--Singular reefs--Slavery--Return to
England--Retrospect on our voyage.

INDEX.

.....

LIST OF ILLUSTRATIONS.

FRONTISPIECE. H.M.S. "BEAGLE" IN STRAITS OF MAGELLAN. MT.
SARMIENTO IN THE DISTANCE.

PLATE 1. H.M.S. "BEAGLE" UNDER FULL SAIL, VIEW FROM ASTERN.

PLATE 2. H.M.S. "BEAGLE": MIDDLE SECTION FORE AND AFT, UPPER
DECK, 1832.

PLATE 3. FERNANDO NORONHA.

PLATE 4. INCRUSTATION OF SHELLY SAND.

PLATE 5. DIODON MACULATUS (Distended and Contracted).

PLATE 6. PELAGIC CONFERVAE.

PLATE 7. CATAMARAN (BAHIA).

PLATE 8. BOTOFOGO BAY, RIO DE JANEIRO.

PLATE 9. VAMPIRE BAT (Desmodus D'Orbigny).

PLATE 10. VIRGIN FOREST.

PLATE 11. CABBAGE PALM.

PLATE 12. MANDIOCA OR CASSAVA.

PLATE 13. RIO DE JANEIRO.

PLATE 14. DARWIN'S PAPILIO FERONIA, 1833, NOW CALLED AGERONIA
FERONIA, 1889.

PLATE 15. HYDROCHAERUS CAPYBARA OR WATER-HOG.

PLATE 16. RECADO OR SURCINGLE OF GAUCHO.

PLATE 17. HALT AT A PULPERIA ON THE PAMPAS.

PLATE 18. EL CARMEN, OR PATAGONES, RIO NEGRO.

PLATE 19. BRAZILIAN WHIPS, HOBBLES, AND SPURS.

PLATE 20. BRINGING IN A PRISONER.

PLATE 21. IRREGULAR TROOPS.

PLATE 22. SKINNING UJI OR WATER SERPENTS.

PLATE 23. RHEA DARWINII (Avestruz Petise).

PLATE 24. LANDING AT BUENOS AYRES.

PLATE 25. MATE POTS AND BAMBILLIO.

PLATE 26. GIANT THISTLE OF PAMPAS.

PLATE 27. CYNARA CARDUNCULUS OR CARDOON.

PLATE 28. EVENING CAMP, BUENOS AYRES.

PLATE 29. ROZARIO.

PLATE 30. PARANA RIVER.

PLATE 31. TOXODON PLATENSIS. (Found at Sal