38 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



northeastern exti'emity; it follows irregularly the outline of the shore at 

 a distance varying from one to over two miles. The outer reef off the 

 north coast is broken into distant patches, leaving broad passages between 

 them. North of the western passage the reef is also interrupted, leaving 

 a boat passage. The outer reef flats are irregularly trapezoidal in out- 

 line, and quite narrow. The greatest depth in the outer lagoon is 27 

 fathoms. The eastern arm, and also the northern horn of the lao'oon 

 and tlie inner edge of the southern face of the outer reef, aj-e studded 

 with rocks and coral patches. The coi-als on the reef flats are thrivino-, 

 and those on the patches inside of tlie lagoon are everywhere most flour- 

 ishing. Many of the patches close to the outer shore line are in the 

 extension of lateral spurs which have been eroded from the ridge of the 

 rim. The general depth of the outer lagoon is over 20 fathoms alone 

 its central channel. Similar spurs run into the inner basin, and have 

 formed extensive spits on which corals flourish, or islets and islands such 

 as those figured on Plate 69, near the inner edge of the northern rim of 

 Totoya. Near the centre of the basin there is an extensive coral patch, 

 Kini Kini (Plate 23), formed upon the sides of a small islet rising from 

 the bottom of the crater, as is so often the case in the craters of other 

 volcanoes (see Plate 71). The volcanic rocks forming its centre are 

 exposed at low water. The outer rim of the crater of Totoya has a 

 diameter of six miles; it slopes quite evenly from the crest of the ridge 

 to the outer and inner shore line ; the slopes are cut by compara- 

 tively shallow valleys, separated by ridges with rounded crests. (Plates 

 €7, 69.) 



The water which pours into the inner basin over the barrier stretching 

 across the horns of the crater finds its only outlet through the " Gullet," 

 where it rushes thi-ough with considerable velocitv. The scourins' effect 

 of the waters rushing out of lagoons has been noticed by all who have 

 navigated among coral reefs, and the strong currents flowing out of the 

 lagoons through the encircling reefs of openings are constantly referred 

 to in the sailing directions. 



In the extension of the western horn of the crater on the west of the 

 " Gullet," are two small islets (Plate 68), the remnants of a part of the 

 southern rim of the crater. Small islets also exist off" the west coast, on 

 the northern side of the isthmus. They are remnants of one of the 

 spurs putting out from the west side of the outer rim. From what we 

 have seen in Totoya, there is little doubt that the fringing reefs, the 

 shore flats, the coral patches, and in different parts of the lagoon the outer 

 reef flats are the remants of flats formed by the denudation and subma- 



