Henry Woodward — Daion of Life on the Earth. 293 



From certain prevalent organisms found in it, sueli as shells of 

 Oysters, Ammonites, Nautili, Starfishes, and Ecliinoderms, bones and 

 teeth of fishes, geologists rightly conclude it to be a truly marine 

 deposit. 



But of what is the great bulk composed ? Is it merely a finely 

 comminuted white mud? — for such it seems to be to the unassisted 

 eye. No ; when washed and examined beneath the microscope, we 

 find it to consist almost wholly of two distinct minute organisms. 



The general mass of it is made up of very minute granules ; but 

 imbedded in this matrix are innumerable bodies, some smaller, some 

 larger, but on a rough average not more than a hundredth of an inch 

 in diameter, having a well-defined shape and structure. A cubic 

 inch of some specimens of chalk may contain hundreds of thousands 

 of these bodies, compacted together with incalculable millions of the 

 granules. 



The larger bodies when separated prove to be each one a beauti- 

 fully constructed calcareous fabric made up of a number of chambers, 

 communicating freely with one another. The commonest of these is 

 called Globigerina, and sometimes seems to compose nearly the 

 entire mass of the chalk. 



In the soundings carried out by Captain Dayman, E.N., in con- 

 nexion with the laying of the submarine cable between Ireland and 

 Newfoundland, it was ascertained that almost the whole floor of the 

 great central lolain of the Atlantic, more than 1000 miles across from 

 east to west, and which extends for many hundred miles in a'north 

 and south direction, is covered (at a depth of 1700 fathoms) by fine 

 mud, which, when brought to the surface, dries into a greyish- white 

 friable substance resem^bling soft grey chalk. When examined under 

 the microscope, it proves to be composed of innumerable GlobigerinoR 

 (together with Diatoms) imbedded in a granular matrix. 



Thus, then, this deep-sea mud is substantially like the Chalk. 

 Prof. Huxley (upon whom the task devolved of examining these 

 deep-sea soundings) was surprised to find the '•' granules " of the 

 mud in which the Globigerince abound had a definite form and size. 

 He named these bodies coccoliths, but doubted their organic origin. 

 Dr. Wallich, who accompanied Sir Leopold M'Clintock, in 1860, in 

 the cruise of II.M.S. " Bull-dog," verified these observations of 

 Huxley's, and added the interesting discovery that not unfrequently 

 bodies similar to these co-ccoUths were aggregated together into 

 spheroids, which he termed coccospheres. 



Mr. H. C. Sorby, F.K.S., in making a careful microscopic ex- 

 amination of the chalk, observed, as Ehrenberg had done before him, 

 that much of its granular basis possesses a definite form. Comparing 

 these formed particles with those in the Atlantic soundings, he 

 found the two to be identical ; and thus proved that the chalk, like 

 the soundings, contains these mysterious coccoliths and coccospheres, 

 as well as the shells of Glohigerince. Professor Huxley has since 

 traced out the development of the " coccoliths " from a diameter of 



with formidable jaws, which once inhabited the valley of the Meuse. The Leiodon, 

 Owen, from the Upper Chalk near Norwich, is closely allied to the Mosasaurus.. 



