STRUCTURE OF CORAL ISLANDS. i6i 



with no entrance. North-east side alone wooded, and in two 

 patches. 



Tcku Or Four Crowns, Paumotu Archipelago. — 20° 28' S. 

 143^ 18' W. Diameter i| miles, nearly circular. A small 

 lagoon with no entrance. South-western reef bare ; five patches 

 of forest on the other part. 



Washington Island. — Lat. 4° 41' N. Long. 160° 15' W. 

 3 miles by i^, trending east and Avest. It is a dense cocoa-nut 

 grove with luxuriant shrubbery. No lagoon. The shore plat- 

 form is rather narrow. A point of submerged reef, one-and- 

 a-half miles long, stretches out from the southwest end. Did 

 not land on account of bad weather. 



Enderbiu-ys.— -^ 8' S. 171"^ 15' W. 2| miles by i mile 

 nearly, trending N. N. W. and S. S. E. ; form trapezoidal or 

 nearly rectangular. Little vegetatiori on any part, and but few 

 trees. The lagoon very shallow, and containing no growing 

 coral ; its shores of coral mud, allowing the foot to sink in 

 eight or ten inches, and covered in places with saline incrusta- 

 tions. Shore platform one hundred feet or less in width, and 

 surface inclined outward at a very small angle ; covered with 

 three or four feet of water at high tide, and with few corals or 

 shells; beyond this, falls off four to six feet, and then the 

 bottom inclines for one hundred yards or more. The beach 

 very high and regular ; rises eight feet at an inclination of 

 thirty to thirty-five degrees ; then horizontal for eighty to two 

 hundred, after which another rise of three or four feet. It 

 consists of pebbles and fine sand, but above of slabs and 

 blocks of coral rock and of the beach sand rock, those of the 

 latter nearly rectangular and flat. This beach sand-rock occurs 

 in layers from ten to twenty inches thick along the shore, 

 and is inclined from five to seven degrees seaward. Some 

 portions are very compact, and ring under the hammer, 

 while others inclose fragments of different sizes to a foot or 

 more in diameter. Large trunks of transported trees lay 

 upon the island, one of which was forty feet long and four 

 in diameter. The shore platform was much intersected by 

 channels. 



