126 THE VOYAGE OF H.M.S. CHALLENGER. 



found on the surface, and were generally covered with small Cirripeds, whilst in some 

 instances they were completely enveloped by species of Acineta and Podophrya. 



The character of the deposits in this section presented considerable variety. With 

 the exception of the hard ground already referred to, composed of manganese and coral, 

 all the deposits in depths less than 2500 fathoms contained more than 50 per cent, of 

 carbonate of lime. For these the names Globigerina and Pteropod oozes have been 

 adopted, the latter being confined to two deposits from the depths of 1420 and 

 450 fathoms on the western side of the section, in which occurred very many Pteropod 

 and Heteropod shells, in addition to pelagic and other Foraminifera, and in which the 

 proportion of carbonate of lime was the greatest, being 80 to 84 per cent. Only a 

 few fragments of Pteropods were found in the Globigerina ooze, from depths ranging 

 between 1890 and 2500 fathoms, the carbonate of lime being made up chiefly of the 

 dead shelly of pelagic Foraminifera, In depths greater than 2500 fathoms, the quantity 

 of lime decreased as the depth increased, and below 3000 fathoms there were only traces 

 of carbonate of lime in the deposit. 



Siliceous organisms, such as spicules of Sponges, Radiolarians, and Diatoms, were not 

 abundant ; generally they did not appear to make up more than 1 or 2 per cent, of the 

 whole deposit, with the exception of the two deposits at 1420 and 450 fathoms, above 

 referred to, where the proportion rises to about 6 per cent. 



The mineral particles, which were mostly of volcanic origin, seldom exceeded - 15 mm. 

 in diameter, and consisted of felspars, hornblende, augite, magnetite, glassy fragments, and 

 palagonite. In the deposits from the eastern portion of the section there were numerous 

 small rounded particles of quartz covered with ologist, which would appear to be mostly 

 wind-borne particles, carried by the Harmattan and other winds from the coast of Africa. 1 

 The Red Clays from the greater depths were almost entirely composed of argillaceous 

 matter and fine mineral particles not exceeding 0"05 mm. in diameter. In the dredging 

 on the 7th March in 2435 fathoms, there were several round compact manganese 

 nodules, pieces of pumice several millimetres in diameter, and three or four Sharks' teeth 

 coated with peroxide of manganese. 



St. Thomas, Virgin Islands. 



As the ship steamed towards the harbour at St. Thomas, Frigate Birds soared high 

 overhead, with their long tail feathers stretched widely out. A number of brown 

 Pelicans (Pelecanus fiiscus) were flying at a moderate height near the shore, and every now 

 and then dashing down with closed wings into the water on their prey like their close 

 allies the Gannets. Often several of the birds dashed down together at the same instant. 



The island of St. Thomas itself, as well as the outlying islets, is covered with a wild bush 



1 See Darwin, Journal of Researches during the Voyage of H.M.S. "Beagle," p. 5, ed. 1879. 



