21 



markable that the converse of this supposition has actually obtained, 

 and our modern seas have yielded living forms hitherto characteristic 

 of the chalk formation, and regarded as antediluvial. The merit of 

 this discovery rests with Prof. Ehrenberg. His elaborate researches 

 were communicated to the Royal Academy of Berlin, and translations 

 of the original papers, by Mr. Francis, have been published in this 

 country in Taylor's ' Scientific Memoirs.' 



I have now the pleasure of communicating to the Microscopical 

 Society some observations of my own which confirm all the important 

 conclusions arrived at by Ehrenberg, and are fortunately capable of 

 easy verification. It will not be necessary to send for sea-mud from 

 Norway, or for Peruvian or Mexican sea-water ; half-a-dozen native 

 oysters, or, in truth, I may say, the stomach of a single oyster, will 

 often afford us ample proof of the uniformity and identity of organic 

 life in distant ages of the earth, and leave us in no doubt that the 

 dawn of the organic creation co-existent with ourselves, reaches fur- 

 ther back into the history of the earth than has hitherto appeared. 



The well known ciliary currents in the fringes of the oyster, in- 

 duced me to examine the contents of the stomach, under the expec- 

 tation of finding some minute forms of Infusoria ; for it seemed but 

 reasonable to infer that the absence of locomotive power and the con- 

 sequent inability of seeking for food, might be compensated by so 

 beautiful a contrivance for ensuring constant nourishment. My ex- 

 pectations were fulfilled and surpassed. In the stomach of every 

 oyster I examined, and in the alimentary canal, I found myriads of 

 living monads, the Vibrio also in great abundance and activity, and 

 swarms of a conglomerate and ciliated living organism, which may be 

 named Volvox ostrearius, somewhat resembling the Volvox Globator, 

 but of so extremely delicate a structure, that it must be slightly char- 

 red to be rendered permanently visible. 



This result, though highly interesting in itself, and marking so 

 clearly the especial function of those instruments which fit the oyster 

 for its peculiar place in the scale of created beings, is nevertheless of 

 inferior importance, in a geological point of view, to some other re- 

 sults to which the presence of other Infusoria in the stomach of the 

 oyster conduct us. These Infusoria I will briefly enumerate. They 

 have siliceous loricae, and belong to the family of the Bacillarice, 

 and some of these in their fossil state constitute the chief bulk of the 

 chalk. 



