18 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
voleanic,' 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 Horne, have a very considerable extension both in Viti 
Levu and in Vanua 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 paleozoic 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 Horne, 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 toa 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. I. 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. 
