ON A PIECE OF CHALK 73 



It has been observed, again, that the abundance of Glo- 

 bigerincB, in proportion to other organisms, of like kind, in- 

 creases with the depth of the sea; and that deep-water 

 GlohigerincB 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 wonderful creatures live and 

 die at the depths in which they are found. ^ 



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

 GlobigerincB 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 

 Globigerince of the chalk differed from those of the existing 

 species. But if this be true, there is no escaping the conclu- 

 sion 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 "granules" of that mud were not, as one might 

 have been tempted to think at first, the mere powder and 

 waste of Globigerince, but that they had a definite form and 

 size. I termed these bodies ^' coccoliths,^^ and doubted 



1 During the cruise of H.M.S. Bulldog, commanded by Sir Leopold 

 M'Clintock, in i860, living star-fish were brought up, clinging to the 

 lowest part of the sounding-line, from a depth of 1,260 fathoms, mid- 

 way between Cape Farewell, in Greenland, and the Rockall banks. 

 Dr. Wallich ascertained that the sea-bottom at this point consisted of 

 the ordinary Glohigerina ooze, and that the stomachs of the star-fishes 

 were full of GlobigerincB. This discovery removes all objections to the 

 existence of living Globigerince at great depths, which are based upon 

 the supposed difficulty of maintaining animal life under such con- 

 ditions; and it throws the burden of proof upon those who object to the 

 supposition that the Globigerince live and die where they are found. 



