196 CORALS AND CORAL ISLANDS. 
to 21° 8. Several of them are guano islands, as described 
on pages 318 to 324. 
Birnie’s. — Lat. 3° 35’ 8. Long. 171° 30’ W.  Four- 
fifths of a mile by one-third, trending northwest. No lagoon. 
A sandy flat about ten feet high, except near the north-north- 
east extremity, where it is about twelve feet. To the south- 
southwest the submerged reef extends out nearly a mile, over 
which the sea breaks. In passing it, distinguished no vegeta- 
tion except the low purslane and some trailing plants. 
Enderbury’s. — 3° 8S. 171° 15’ W. 4 miles by 1 mile 
nearly, trending N. N. W., and 8. 8. E.; form trapezoidal or 
nearly rectangular. Little vegetation on any part, and but 
few trees. The lagoon very shallow, and containing no grow- 
ing coral; its shores of coral mud, allowing the foot to sk in 
eight or ten inches, and covered in places with saline incrus- 
tations. 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 ham- 
mer, while others enclose 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 
