AGASSIZ: FIJI ISLANDS AND CORAL REEFS. 9 
building up columnar masses which may eventually reach the surface 
forming mushroom- or even bell-shaped structures, of which enlarging 
rims may meet, “resulting in the formation of a connected reef surface 
supported by many upright pillars underneath from forty to fifty feet 
high,” the so called ‘“ chapeiroes” of the Portuguese. These patches fre- 
quently occur near the shore along the margin of a fringing reef, but are 
best developed in the deeper water of the Abrolhos regions and between 
these and the city of Bahia, growing upon the submerged rocky ledge. 
The number of reef building corals in Brazil is quite small, and Nulli- 
pores seem according to Rathbun to play a very important part in the 
building up of the limestone reefs. 
Professor Bonney? summarizes the position of the theory of coral reefs 
as now left (1889) in the following terms: ‘‘ That this theory may have 
been expressed in terms a little too comprehensive, that there may be a 
larger number of exceptional cases than was at first supposed, is quite 
possible. . . . It may very possibly be found that, as remarked by 
Mr. Bourne, the history of coral reefs is more varied and complicated 
than was at first supposed, but it seems to me that, as the evidence at 
present stands, it is insufficient to justify a decision adverse to Mr. Dar- 
win’s theory as a general explanation.” 
Professor Bonney, in spite of his intention to present an absolutely 
unbiassed expression, has, in common with most geologists not familiar 
with coral reefs, retained the view of the correctness of Darwin’s theory.” 
It can scarcely be said that the earlier examinations of coral reefs were 
made with the detail which has characterized the later explorations. 
The original work of Darwin was limited to a narrow field, and sup- 
plemented by data derived from charts and descriptions. Its correct- 
ness depends wholly upon the existence of masses of coral reefs of great 
thickness, where coral reefs exist as barrier reefs or atolls, and having 
assumed this the rest naturally followed. For no one will deny that sub- 
sidence is one of the possible modes of formation of masses of limestone 
of great thickness. But subsequent observers showed most distinctly 
that both atolls and barrier reefs occurred in regions of elevation. These 
exceptions are not limited to a single area. They occur in regions of 
the globe widely separated. While it undoubtedly is true, as remarked 
1 Loc. cit., p. 832. 
2 Dana’s support of Darwin’s theory, based as it was upon very great ex- 
perience among coral reefs, has probably been the principal cause of the gen- 
eral acceptance of the theory in late years, in spite of the attacks of recent 
investigators. 
