IX .] ON A PIECE OF CHALK. 161 



along with the Diatoms and Radiolaria, in the uppermost stratum 

 of the open ocean. 



It has been observed, again, that the abundance of Gloliyerince, 

 in proportion to other organisms, of like kind, increases with the 

 depth of the sea; and that deep-water Globigerincc are larger 

 than those which live in shallower parts of the sea ; and such 

 facts negative the supposition that these organisms have 

 been swept by currents from the shallows into the deeps of 

 the Atlantic. 



It therefore seems to be hardly doubtful that these won 

 derful creatures live and die at the depths in which they are 

 found. 1 



However, the important points for us are, that the living Glo- 

 bigerince are exclusively marine animals, the skeletons of which 

 abound at the bottom of deep seas; and that there is not a 

 shadow of reason for believing that the habits of the Globigcrincc 

 of the chalk differed from those of the existing species. But if 

 this be true, there is no escaping the conclusion that the chalk 

 itself is the dried mud of an ancient deep sea. 



In working over the soundings collected by Captain Dayman, 

 I was surprised to find that many of what I have called the 

 &quot;granules&quot; of that mud were not, as one might have been 

 tempted to think at first, the mere powder and \vaste of Gloli- 

 gerince, but that they had a definite form and size. I termed 

 these bodies &quot; coccoliths,&quot; and doubted their organic nature. Dr. 

 Wallich verified my observation, and added the interesting dis 

 covery that, not unfrequently, bodies similar to these &quot; coccoliths &quot; 

 were aggregated together into spheroids, which he termed 



1 During the cruise of H.M.S. Bull-dog, commanded by Sir Leopold 

 M Clintock, in 1860, living star-fish were brought up, clinging to the lowest 

 part of the sounding-line, from a depth of 1,260 fathoms, midway between 

 Cape Farewell, in Greenland, and the Rockall banks. Dr. Wallich ascer 

 tained that the sea-bottom at this point consisted of the ordinary Globigerina 

 ooze, and that the stomachs of the star-fishes were full of GlobigerincB. 

 This discovery removes all objections to the existence of living Gloligerince 

 at great depths, which are based upon the supposed difficulty of maintaining 

 animal life under such conditions ; and it throws the burden of proof upon 

 those who object to the supposition that the Globigerince live and die where 

 they are found. 



