54 bulletin: museum of comparative zoology. 



Vatu Vara or Hat Island (Plate 19) is one mile and a quarter in 

 diametei-. Its summit is flat, and falls off on all sides in steep cliffs. 

 It attains an altitude of 1,030 feet. The cliffs consist of elevated lime- 

 stone standing out conspicuously through the dark foliage which covers 

 the island from base to summit. Up to the very summit of the island 

 the exposed rocks are seen to consist of limestone. The island is 

 surrounded by a fringing reef nearly a mile in width on the west coast. 

 On the east and north sides the sea breaks against the neai'ly vertical 

 limestone cliffs. They are deeply undercut. On the northwest side two 

 separate masses of limestone stand out midway between the base of the 

 cliffs and the outer edge of the reef. An incipient lagoon, open to the 

 north, is forming along a part of the west coast of the island. 



Yathata and Kaimbo. 



Plate 19. 



The islands of Yathata and Kaimbo (Plate 19), which rise respectively 

 to the height of 840 and 150 feet, are composed of elevated limestone 

 rock. A fringing reef encloses them both. It attains a width of over 

 half a mile where it connects the islands, and is nearly a mile wide 

 off the north of Yathata. Off that shore a number of small islets and 

 heads stand out between the island and the outer edge of the reef. Else- 

 where the frincrinK reef is narrow. Between the islands in the middle of 

 the fringing reef stands out the i.slet of Nuku Levu, *J0 feet in height, 

 and a few heads. There appears to have been a secondary elevation on 

 the south side of Kaimbo, where the undercut ledge has been raised about 

 twenty feet above high water mark. 



I am informed by Captain R. Cocks that Katavanga is composed of 

 elevated limestones. 



Aiwa. 



Plates 21, 23*, Figs. 13-15. 



Aiwa consists of two small elongated islands, the western one of which 

 is not quite a mile in length (Plate 21). Both are composed of elevated 

 limestone, pitted and honeycombed, forming low vertical bluffs along 

 their southern faces. The highest points of the islands are respectively 

 210 and 200 feet. They are connected by a coral reef awash at low 

 tide. The islands are in the middle of the southern face of the outer 

 reef flat, which encloses an elongate narrow triangular lagoon nine miles 



