82 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
the atolls or islands encircled by recent coral reefs beyond forming the 
substratum upon which the recent corals have grown and established 
themselves as a comparatively thin crust. 
The underlying limestones have performed exactly the same part as 
the volcanic substratum in other islands of Fiji, such as Totoya, Kim- 
bombo, Wakaya, Makongai, Moala, Nairai, Ngau, and others. In both 
cases the platform upon the edge of which the corals grow has been 
prepared by extensive submarine erosion, dating from the time when the 
limestones were elevated by the volcanic rocks which crop out everywhere 
in Fiji, —an elevation which was not necessarily synchronous throughout 
Fiji and may have taken place at several distinct periods, so as to make 
it often difficult to determine the relative age of the limestones and of 
the volcanic masses. 
Professor David, of the University of Sydney, has been kind enough to 
assist me in obtaining the services of one of his students, Mr. E. C. 
Andrews, to collect fossils from the elevated limestones of Fiji. Mr. 
Andrews has spent a part of the summer in Fiji, collecting material and 
exploring in detail some of the faces and slopes of the elevated reefs of 
the Archipelago, and has obtained ample material to determine the age 
of these elevated limestones. 
In the earlier discussions of the thickness of recent coral reefs by 
Darwin and Dana, no attention was paid to the possibility of the sub- 
stratum of recent reefs consisting of tertiary limestones. Elevated lime- 
stones containing corals of tertiary age were considered as of recent 
origin and as pointing to a great thickness of modern reefs. It has 
been shown in Florida that the modern reef is not more than about 
50 feet thick, and is, according to the borings from the artesian well at 
Key West, succeeded by tertiary limestones, in which corals oceur at 
intervals to a depth of 2,000 feet. 
It has been stated by Dana and others that the borings from the 
artesian wells at Honolulu, to the rear of the shore line of the fringing 
reef of Oahu, indicate a great thickness of modern reef corals. These 
statements are based upon the examination of samples of finely ground 
particles of limestone accompanied by an occasional fragment of coral, 
the age of which has not been determined. The statements are further 
supported by the evidence of Mr. J. A. McCandless, the engineer in 
charge of the boring, who asserted to both Mr. Dana and myself that in 
boring all his wells the tool passed through a great thickness of corals, at 
various levels. During my recent visit at Honolulu, I was so fortunate as 
to be on the spot where Mr. McCandless was boring a ten-inch well, about 
