ST. THOMAS. 17 



general mass as a background. The spines look as if they 

 ended where the white colouring ends, and the hand is advanced 

 as if the prickles began there, and is pricked suddenly by some 

 unseen black tip. The experiment is easily tried in any cactus 

 house at home. 



In the beach of Little Saba Island there was being formed a 

 reddish sandstone conglomerate rock composed of the cUbris 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 (T. 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 1,000 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 Island grew a number of plants 

 of Guilandina bonduc. 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, especially 

 two species of the genus madrepora named from their resemblance 

 to antlers, Madrepora cervicornis and M. alcicomis. I saw at 

 Little Saba Island, a Brain-coral which measured four feet in 

 diameter of 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. 



C 



