APPEARANCE OF THE REEFS. 161 



structure, and left the matter for the judicious deci- 

 sion of some of the professors of comparative anatomy 

 at home." 



It may here be remarked that the birds met with 

 on Houtman's Abrolhos, with the exception of one, 

 resembling in shape and colour a small quail,* were 

 known and common on the main land. The aquatic 

 species were also familiar to us ; but the habit of 

 one kind, of a sooty-black colour, generally called 

 noddies, was quite new — that of building their nests, 

 which are constructed of sea- weed and contain only 

 one egg, in trees. There were not many varieties of 

 fish, the most abundant being snappers ; of those that 

 were rare Lieut. Emery made faithful sketches. 



Half a mile west from Slaughter Point we found 

 two caverns similar to that on East Wallaby Island, 

 from which we got three tons of excellent water. 

 The reefs surrounding this group appeared very 

 much broken ; and even at Easter Group we had 

 found them to be not so regular as at Pelsart's. 

 This suggests the idea, which appears to be borne 

 out by all we saw, that the reefs are compact in pro- 

 portion to the exposed position of the islands ; the 

 shelter afforded by Pelsart Group, in fact, did not 

 require the reefs to be so united round the other 

 islands to the north. 



From the highest part of East Wallaby Island we 

 discovered a patch of land bearing N. W. ^N. eleven 

 miles. The outer reef extended in that direction 



* Hcemapodicus Scintilans, Gould. 

 VOL. 11. M 



