Cliap. i.] LITTLE SABA ISLAND. 15 



of the rock of which the higher parts of the island consist, 

 cemented together by calcareous matter derived from the 

 corals and calcareous sand. This rock, which was hard and 

 compact, contained embedded in it plenty of the various corals 

 from the beach and large Turbo shells (Z! pica), with their 

 nacre quite fresh in lustre, and their bright greenish colour 

 unimpaired. 



Large examples of these Turbo shells, as much as two inches 

 in diameter at the base, are in St. Thomas carried up far 

 inland by terrestrial Hermit-crabs. I saw a large number of 

 them amongst the bush at an elevation of i,ooo feet, some of 

 them with the crabs in them, many empty. These large heavy 

 sea shells, occurring in abundance at great heights, puzzled 

 geologists until it was found that they were carried up by the 

 crabs. 



On the shore at Little Saba Lsland grew a number of plants 

 of Guilandina boiiduc. This plant bears a pod covered with 

 prickles which contains nearly spherical beans of about the size 

 of a hazel nut, which have a perfectly smooth, as it were, 

 enamelled surface, and are flinty hard. These seeds float, and 

 are carried by ocean currents to distant shores, and are in 

 Tristan da Cunha and Bermuda known as " Sea-beans," and 

 supposed to grow at the bottom of the sea. Don Jose de Canto 

 showed me one found in the Azores. 



The coral reefs of St. Thomas are remarkable for the large 

 size and luxuriant growth of certain corals upon them, especi- 

 ally two species of the genus madrepora named, from their 

 resemblance to antlers, Madrepora cerviconiis and M. alcicomis. 

 I saw, at Little Saba Island, a Brain-coral which measured four 

 feet in diameter at the base and three feet in height. 



A list of the flowering plants of St. Thomas, and other information, is 

 given in "A Historical Account of St. Thomas, W. I."' By J. P. Knox. 

 New York, Charles Scribner, 1852. 



Bermuda, April 5th to 21st, and May 27th to June 12th, 1873. 



— Bermuda is entirely a coral island, that is to say, the com- 

 plete mass of the island now above water, and that below sea 

 level, as far at least as excavations which have been made have 

 extended, has been brought together by the agency of lime- 

 secreting animals and plants, aided by the winds and waves, 

 and alterations in the height of the sea-bed. It is the most 

 distant coral island from the equator, lying about 9° of latitude 

 north of the Tropic of Cancer, in about the same latitude as 

 Madeira, which island has, however, no coral reefs. It is 

 distant from Cape Hatteras, the nearest point of the American 

 coast, about 600 miles. 



