18 bulletin: museum of comparative zoology. 



volcanic,^ a division which Lister had previously applied to the Tonga 

 group. Gardiner was, as we were, struck with the difference in the 

 physiognomy of the islands, the volcanic islands, with their gentle slopes, 

 rounded summits, or conical peaks, being in striking contrast to the flat- 

 topped hills with precipitous sides, and the glistening white cliffs of the 

 islands consisting of elevated coralliferous limestones. 



I obtained from various localities in Viti Levu specimens of the 

 older crystalline rocks belonging to the same series, which, according to 

 Wichman '^ and Home, have a vei-y considerable extension both in Viti 

 Levu and in Vauua Levu. The tufas 'and conglomerates are in many 

 instances fossilliferous, and are considered by Martin as tertiary, not 

 older than miocene. Wichman concludes that the larger islands must 

 have existed as a continent during mesozoic and palaeozoic periods, and 

 that oscillations of level only took place in latest tertiaries. From the 

 specimens examined by him, Wichman also concludes that Kandavu, 

 Ovalau, Ono, and some of the Exploring Isles consist principally of 

 andesites and basalts, and their tufas. According to Home, Taviuni 

 is the only island of the group which is of purely volcanic origin. This 

 certainly is not the case. I would mention, among others, Moala, 

 Thombia, and Totoya.^ 



VOLCANIC ISLANDS, 



Koro. 



Plates 3*, 19^^, Fig. 8. 



Koro is one of the larger volcanic islands which has not been greatly 

 affected by submarine erosion. It is about ten miles long with a north- 

 ern face of five, the east and west sides run to a point. The shores, 

 with the exception of the southern part of the west coast, which runs 

 nearly north and south, are bordered by a fringing reef extending about 

 a mile and a half from shore ; on the east coast the fringing reef is cut 

 into small incipient lagoons (Nangaidamu Harbor), and has several boat 

 harbors, generally opposite the mouth of a small river. On the north 

 coast the reef patches extend nearly four miles from shore, forming an 



1 Proc. Camb. Phil. Soc, Vol. IX. Part VIII. p. 457 (1898). 



2 Min. u. Petrog. Mittheil. v. Tschermak, Vol. V. Pt. L p. 1 (1882). 



3 The specimens of rocks we collected in Fiji at the different islands are now 

 under examination, and a report on them will follow later. 



