FORAMINIFEEA IN THE RAISED REEFS OF FIJI. 363 



Amphistegina occurs in eleven slides, and is often abundant, as is the 

 case in the rock from Eua, 120 ft. 



Although rotaline Foraminifera occur in many of the slides, no form is 

 common. The most generally occurring genera are Planorbulina and 

 Truncatulina. Globigerina occurs in four slides. Orbitoides is of espe- 

 cial interest, as it is not found in rocks younger than the Miocene. In- 

 dividuals are very numerous in the section from Mango, 310 ft., and it 

 is noteworthy that the genus is entirely absent from the other Mango 

 specimens examined. 



The Niue rocks are characterized by the great number of tunicate 

 spicules which they contain. The first described occurrence of these 

 organisms as fossils was in the Pliocene of St. 

 Erth, Cornwall, where Messrs. Kendall and Bell 

 found spicules referred by Dr. G. J. Hinde to 

 Leptoclinum. 1 Professor Herdman had pre- 

 viously pointed out that calcareous spicules oc- 

 curred in many genera of Tunicata, and were as 

 capable of preservation as the aragonite skeletons 

 of other organisms. 2 As, however, with the ex- 

 ception of the St. Erth beds above-mentioned. 

 , , , , , . Fig. 13. Nine, \ ailoa, 



they do not seem to have been found in the ^ f t Tunicate spicule 



fossil condition, their occurrence in the coral (Leptoclinum), surface 

 reefs of Niue becomes of interest. view, x o00. 



Although Niue (Savage Island) is situated between the Tonga and 

 Fiji Groups, and the rocks of all three places resemble each other in 

 structure and composition, the tunicate spicules appear to be confined to 

 Niue (with the doubtful exception of Ngillingillah). They also occur, 

 however, in the rocks from Christmas Island collected by Dr. C. W. 

 Andrews, and in the Funafuti boring described by Dr. G. J. Hinde. 

 In all three cases, Niue, Christmas Island, and Funafuti, the spicules 

 seem identical and belong to the same genus, Leptoclinum Milne 

 Edwards, as occurs at St. Ei'th. 



The number of spicules present in the rocks also varies widely. All 

 the slides which are not simply sections of a coral mass, show some 

 spicules, but they are particularly abundant in the black mud. In 

 many cases, circular areas of clear granular calcite occur having the 

 usual size of the spicules, but showing no structure. These clearly 

 represent the spicules which have been altered into calcite and their 



J Quart. Journ. Geol. Soc. Lond., XLII. pp. 201-215. 

 2 Proc. Geol. Soc. Liverpool, 1884-85, p. 42. 

 vol. xxxvin. — no. 8 2 



