146 CORALS AND CORAL LSLANDS. 



shaped. Another mass, similarly attached to the reef at base, 

 observed on Kawehe (Vincennes Island), was six feet high 

 above low-water level, and seven feet in its longest jdiameter. 

 Below, it had been worn like the one just described, though 

 to a less extent. Another similar mass was eight feet high. 

 Figure 2 represents a block six feet high and ten feet in its 

 longest diameter, seen on Water] and ; it was' unattached be- 

 low, and lay with one end raised on a smaller block. On 

 Aratica (Carlshoff), others were observed. One loose mass 

 like the last was eight feet high and fifteen feet in diameter, 

 and contained at least a thousand cubic feet. Raraka also 

 afforded examples of these attached and unattached blocks, 

 some standing with their tops six feet above high-water mark. 



These masses are similar in character to many met with 

 among the fields of blocks just described, and differ only in 

 having been left on the platform instead of transported over it. 

 Some of them are near the margin of the reef, while others are 

 quite at its inner limit. The second mass alluded to above, on 

 Kawehe, was a solid conglomerate, consisting of large fragments 

 of Astreeas and Madrepores, and contained some imbedded 

 shells, among which an Ostrasa and a Cypraea were noticed. 

 This is ,their usual character. The other two were parts of 

 large individual corals (Porites) ; but there was evidence in the 

 direction of the cells that they did not stand as they grew ; on 

 the contrary, they had been upthrown, and were afterward 

 cemented with the material of the rock beneath them, probably 

 at the time this rock itself was consolidated. Below some of 

 the loose masses the platform was at times six inches higher 

 than on either side of the mass, owing to the protection from 

 wear given to tlie surface beneath it. These blocks are always 

 extremely rough and uneven, like those of the emerging land 

 beyond ; and the angular features are partly owing, in both 

 cases, to solution from rains and from the dashes of sea-water 

 to which, with every tide, they are exposed. 



It should be distinctly understood that these masses here 

 described were found isolated, and only at considerable inter- 

 vals. In no instance were they observed clustered. The loose 



