—— 
AGASSIZ: FIJI ISLANDS AND CORAL REEFS. 13k 
a fringing reef flat covered with Alcyonarians (Plate 76), similar to 
those figured by Kent. 
Gardiner has observed the important part which incrusting coralline 
alge perform in Fiji in supplying the material for a reef rock of compact 
homogeneous structure ; they undoubtedly assist materially in prevent- 
ing the disintegration of dead corals, and their subsequent commiuution 
by the action of the waves. In an interesting article on the calcareous 
alge of the Gulf of Naples,? Walther has given an excellent account 
of the part which coralline alge like Lithothamnium play in building 
up amorphous limestone deposits of considerable thickness from the 
obliteration of its structure.? But he has confused the theory of the 
formation of reefs with the theory of the formation of limestone deposits 
of great thickness, one of which is based on an assumption, the other 
which is not in the least open to doubt. It is evident, however, that 
those who have examined coral reefs have not attributed to coralline 
alge the share which they have in building up recent amorphous lime- 
stone deposits of considerable thickness. 
The following list of algee collected I owe to the kindness of Professor 
Farlow: Amphiroa fragilissima Lam’x ; Galaxaurafragilis Lam’x, var. 
fastigiata Decaisne; Liagora Preissii Louder, var. pacifica Grunow ; 
Padina Pavonia (L.) Gaillon ; Dictyata ciliata J. Ag. sterile ; Turbina- 
ria conoides Kg. ; Hydroelathrus cancellatus Borg.; Sphacelaria furci- 
gera Kg.? sterile; Caulerpa Freycenetii C. Ag.; C. clavifera (Turn.) 
C. Ag.; C. complanata J. Ag.; Halimeda macroloba Decaisne; H. 
Opuntia (L.) Lam’x; H. polydactylis J. Ag.; Aurainvillea comosa 
(Harv.) Murray & Boodle; Aur. papuana Murray & Boodle; Dictyo- 
spheria favulosa Decaisne ; Valonia egagropila (Roth) J. Ag.; Valonia 
utricularis J. Ag. 
ISLANDS AND CORAL REEFS DESCRIBED FROM THE CHARTS. 
With the exception of the Argo Reefs (Plates 19, 20), the islands 
and reefs we did not visit were insignificant in size, or, judging from 
the charts, presented no point of interest not included in those we ex- 
amined. I may mention among these Vanua Vatu (Plate 21), a small 
circular island with a depressed central summit, about a mile and a half 
long. It is composed of elevated coralliferous limestone rising to 310 
1 Loe. cit., p. 477. 
2 Zeitsch. d. deutschen geol. Gesell., Heft 2, Bd. XXXVIL, 1885, p. 329. 
8 See also an article by Fresh, Neues Jahrbuch f. Mineral., 1892, II. 169. 
