EAST-INDIAN ARCHIPELAGO. 229 



in Freycinet's chart to be fringed by coral-reefs ; and mention 

 is made of them in the accompanying Hydrog. Memoir ; 

 coloured red. — Savu, S.E. of Timor, appears in Flinders' 

 chart to be fringed ; but I have not coloured it, as I do not 

 know that the reefs are of coral. — Sandalwood Island has, 

 according to Horsburgh (vol. ii. p. 607), a reef on its 

 southern shore, four miles distant from the land ; as the 

 neighbouring sea is deep, and generally bold, this probably 

 is a barrier-reef, but I have not ventured to colour it. 



N.W. Coast of Australia. — It appears, in Captain King's 

 Sailing Directions (Narrative of Survey, vol. ii. pp. 325 to 

 369), that there are many extensive coral-reefs skirting, 

 often at considerable distances, the N.W. shores, and en- 

 compassing the small adjoining islets. Deep water, in no 

 instance, is represented in the charts between these reefs 

 and the land ; and, therefore, they probably belong to the 

 fringing class. But as they extend far into the sea, which 

 is generally shallow, even in places where the land seems 

 to be somewhat precipitous, I have not coloured them. 

 Houtman's Abrolhos (lat. 28° S. on west coast) have lately 

 been surveyed by Captain "Wickham (as described in Naut. 

 Mag. 1841, p. 511) : they lie on the edge of a steeply- 

 shelving bank, which extends about 30 miles seaward, along 

 the whole line of coast. The two southern reefs, or islands, 

 enclose a lagoon-like space of water, varying in depth from 

 5 to 15 fathoms, and in one spot with 23 fathoms. The 

 greater part of the land has been formed on their inland 

 sides, by the accumulation of fragments of corals; the 

 seaward face consisting of nearly bare ledges of rock. Some 

 of the specimens, brought home by Captain Wickham, 

 contained fragments of marine shells, but others did not ; 

 and these closely resembled a formation at King George's 

 Sound, principally due to the action of the wind on calcareous 

 dust, which I have described in my work on Volcanic Islands. 

 From the extreme irregularity of these reefs with their lagoons, 



