18. 



CHALK ROTALliE. 323 



and is seen to extend to the innermost chamber ; and there 

 is a connecting tube which occupies the place of the 

 siphuncle of the nautilus, for the digestive sacs in the cells 

 are united by the intestinal canal ; minute infusoria which 

 the animal has swallowed, may sometimes be detected in 

 these receptacles. The annexed figure, Lign. 59, represents 

 a recent marine polythalamian deprived of its shell. 



Ligk. 59. — The body of a recent forarniniferous animalcule: the shell having been 



dissolved by acid. From the North Sea, off Cuxhaven. 



{Nonionina Germanica, of EhrenbergO 



Magnified 200 diameters. 



In some of the sacs (a, a,) Navicular and other infusoria swallowed by the animal 



are visible. From Ehrenberg's Memoirs. 



A comparison of this figure, with the specimen in flint 

 (Lign. 51 , p. 303), will show the close analogy between them. 



The soft parts of these foraminifera occur, not only in the 

 flint, but in the white chalk : and by subjecting the latter 

 to the action of dilute hydrochloric acid, the bodies of the 

 rotaliae may sometimes be detected, as distinct in form, as 

 ki this recent specimen from the sea (Lign. 59). I must refer 

 to my observations on this subject in the Philosophical 

 Transactions (for 1846, part iv. p. 465), for further particulars 

 of this remarkable fact. The Eotalias and Textilaria3 are the 

 prevalent foraminifera in the English chalk : and the same 

 t 2 



