22 MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



Tbe drawing from which Figure 3 is engraved was made by George W. Robertson, Esq., 

 of Liverpool, and is accurate. Mr. Arundell describes it very briefly in a letter of January 1st, 

 1884. The plan gives the disposition of the various masses about the central space. The figures 

 in the margins are the elevations of the ten smaller blocks shown in the plan on the borders of the 

 inclosure. The two walls at the ends are not represented in plan, but are revolved 90° so as to 

 appear in elevation. With this explanation the figure can be understood. 



The material of the blocks and walls is coral and coral conglomerate. Mr. Arundell opened 

 cairn C without finding any trace of bones, ashes, or of any human remains. They are situated on 

 the western side of the most northern islet, and there are a few smaller ones on the south point of 

 the longest islet on the eastern side. They must have been built by a native population, but no 

 natives were known to inhabit the island at its first occupation by the whites. 



52. DESCRIPTION OF THE ISLAND. 

 By Prof. E. S. Holden; and Lieut. E. F. Qualtrough, U. S. N. 



Our own observations and the careful survey of the island which was made by Lieutenant 

 Qualtrough and Midshipmen Fletcher and Doyle, enable me to give a tolerably accurate 

 description of Caroline Island. I desire, however, before giving the results of our own work to 

 quote from Professor Dana's Corals and Coral Islands, and from Darwin's Votjatje of the Beagle, 

 their accounts of typical coral atolls which they visited. The only changes necessary in their 

 descriptions, to make these apply exactly to our station, are changes in the dimensions of the 

 ocean reefs, the beaches, etc. The general features of a coral atoll are most perfectly and graphic- 

 ally described by them. To understand their accounts, I may say that the general shape of Caro- 

 line Island is that of a pear-shaped ring of islets, encircling a lagoon. The islets are based on the 

 ocean reef which Dana calls the shore platform. 



Between the islets are portions of this platform, which are nearly bare at low water. Inside 

 the ocean reef is the lagoon, which is itself filled with reefs of corals. Professor Dana says : "The 

 shore platform is from one to three hundred feet in width, and has the general features of a half- 

 s«bmerged outer reef. Its peculiarities arise solely from the accumulations which have changed 

 the reef into an island. Much of it is commonly bare at low tide, though there are places where it 

 is always covered with a few inches or a foot of water; and the elevated [outer] edge, the only 

 l)art exposed, often seems like an embankment preventing the water from running off. The tides, 

 as they rise, cover it with water throughout and bear over it coral fragments and sand, commin- 

 uted shells, and other animal remains, t6 add them to the beach. 



"The heavier seas transport larger fragments; and at the foot of the beach there is often a 

 deposit of blocks of coral, or coral rock, which low tide commonly leaves standing in a few inches 

 of water. On moving these masses, which generally rest on their projecting angles, and have an 

 oi)en space beneath, the waters at once become alive with fish, shrimps and crabs, escaping from 

 their disturbed shelter; and beneath appear various actinise or living flowers, the spiny echini 

 and sluggish heche de mer, while swarms of shells, having a soldier crab for their tenant, walk off' 

 with unusual life and stateliness. Moreover, delicate corallines, ascidia-, and sponges, tint with 

 lively shades of red, green, and pink the under surface of the block of coral which had formed the 

 roof of the little grotto. The beach consists of coral pebbles or sand, with some worn shells, and 

 occasionally the exuviie of crabs and bones of fishes. Owing to its whiteness, and the contrast it 

 attords to the massy verdure above, it is a remarkable feature in the distant view of these islands. 



