152 Cruise of the "Alert." 



just been removed from the bottom of his ship as the copper was 

 being cleaned by native divers. The occurrence is interesting as 

 illustrating the rapidity of the growth of coral in these waters 

 There was the following history : — The Dayot had entered the 

 tropical waters of the South Pacific about seven months previously, 

 having come directly from the coast of Chili. She visited some 

 of the islands, but made no long stay in harbour until she 

 reached Manga Reva (Gambier Islands), where she remained for 

 two months in the still waters of a coral basin. On entering this 

 basin, she touched the reef slightly, and without sustaining any 

 damage. From Manga Reva she sailed to Tahiti, where she 

 arrived about the same time as the Alert. 



Several specimens of living coral were found attached to the 

 copper sheathing, that which I received being the largest. It was 

 discoidal in shape, with its upper and under surfaces respectively 

 convex and concave, and near the centre of the under surface 

 there was a scar, where the pedicle by which it was attached to 

 the copper sheathing appeared to have been broken through. The 

 disc measured nine inches in diameter, and the weight of the 

 specimen, when half dry, was two pounds fourteen ounces. On 

 examining the under surface, another disc, three and three-quarter 

 inches in diameter, was visible, partly embedded in the more recent 

 coral growth. Of this old disc about one-sixth part was dead and 

 uncovered by new coral, and was stained of a deep blue colour 

 from contact with the copper, while the outline of the rest of this 

 old disc was plainly discernible, although partially covered in by 

 plates of new coral. 



It is probable that on touching the reef at Manga Reva nine 

 weeks previously, a young Fungia was jammed against the copper, 

 became attached, and subsequently grew until it attained its 

 present dimensions. 



About midday of the 27th August we arrived off Nassau 

 Island, in latitude 1 1° 31' S., longitude 165 25' W. It is of 

 coral formation, about half a mile long by a quarter of a mile 



