Chalk and Flint of the South-east of England. 83 



Society do not read works of so unpretending a character, and 

 may consider this statement as starthng and unsatisfactory ; I 

 therefore claim the indulgence of entering upon a few details to 

 render the above remarks more intelligible. 



It must be borne in mind that the case or shell of the Rotalia, 

 although presenting the general form, and the internal chambered 

 structure, of the shell of the Nautilus, is essentially different ; for 

 the whole of the external case is perforated with numerous holes 

 or foramina (hence the name Foraminifera), designed for the pass- 

 age of delicate processes called pseudopodia, which are organs of 

 motion ; and the cells or chambers are dissimilar in form, and still 

 more so in their office, from those of the Cephalopoda. For while 

 in the Nautilus the animal occupies only the outer chamber, and 

 all the posterior compartments are successively-quitted empty 

 dwellings, in the Rotalia the body distinctly fills up all the single 

 cells. According to Ehrenberg, the first four cells in the living 

 animal are occupied by colourless matter ; the hinder ones are 

 filled with less transparent parts, consisting of two differently co- 

 loured organs. One of these is the very thick alimentary canal, 

 which forms, like the whole body, a jointed chain expanded in 

 each chamber of the shell, and connected by a narrow isthmus 

 (the sipho ?) with the adjoining anterior and posterior ones. 



M. Ehrenberg dissolved the shell of a living polythalamian, 

 nearly allied to the Rotalia (the Nonionina germanica), by im- 

 mersion in weak hydi'ochloric acid, and thus exposed the ali- 

 mentary canal, which was then seen to be a simple organ dis- 

 tended in the compartments of the body, consequently itself ar- 

 ticulated with a single anterior aperture ; and various siliceous 

 infusoria were distinctly perceived in the digestive tube, having 

 been swallowed by the animal. Beside the alimentary canal, 

 a yellowish brown or amber-coloured granular mass was percep- 

 tible in each of the cells, up to the last of the spirals, the first 

 excepted. 



It was the striking resemblance between the specimen first 

 submitted to my notice, and the figure of the Nonionina deprived 

 of its shell, as given by Ehrenberg, that led me to suspect the 

 true nature of the fossils under review j and the exquisite example 

 which will be placed under the microscope for the inspection of 

 those present, appears to me to leave no doubt of the coiTcctness 

 of that opinion. In the same chip of flint there is another and 

 larger Rotalia, in which the body of the animal also is pre- 

 served. And now that we are accustomed to the microscopical 

 appearance of these organisms, we find that the pale yellowish 

 brown, or amber colour, of many semidiaphanous flints is derived 

 from the soft parts of Rotalice, Textilarice, and other polythala- 

 mian animalcules ; in like manner, as I showed in a paper read 



