Ill EXPEDITION OF THE "CHALLENGER" 71 



the lead sunk several feet into it." A similar 

 " fine green mud " was found to compose the sea 

 bottom in Davis Straits by Goodsir in 1845. 

 Nothing is certainly known of the exact nature of 

 the mud thus obtained, but we shall see that the 

 mud of the bottom of the Antarctic seas is de- 

 scribed in curiously similar terms by Dr. Hooker, 

 and there is no doubt as to the composition of this 

 deposit. 



In 1850, Captain Penny collected in Assistance 

 Bay, in Kingston Bay, and in Melville Bay, 

 which lie between 73 45' and 74 40' N., speci- 

 mens of the residuum left by melted surface ice, 

 and of the sea bottom in these localities. Dr. 

 Dickie, of Aberdeen, sent these materials to 

 Ehrenberg, who made out l that the residuum of 

 the melted ice consisted for the most part of the 

 silicious cases of diatomaceous plants, and of the 

 silicious spicula of sponges ; while, mixed with 

 these, were a certain number of the equally 

 silicious skeletons of those low animal organisms, 

 which were termed Polydstinece by Ehrenberg, but 

 are now known as Eadiolaria. 



In 1856, a very remarkable addition to our 

 knowledge of the nature of the sea bottom in high 

 northern latitudes was made by Professor Bailey 

 of West Point. Lieutenant Brooke, of the United 

 States Navy, who was employed in surveying the 



1 Ueber neue Anschauungen des klcinsten nordlichcn Polar" 

 Icbens. Monatsberichte d. K. Akad. Berlin, 1853. 



