45& SUPPLEMENTARY NOTES. 



the siphon, the air might return by the same passage into the air- 

 chamber, and the lower margin of the valve fall into its socket 

 within the lower collar (i.) 



It is possible that in the Spirula and other animals that do not 

 withdraw their bodies into the shell, the only function of the air- 

 chambers may be to counterbalance the weight of the body, and 

 give it buoyancy; in such cases the use of the siphuncle may be 

 to carry down to the extremity of the shell, and send off into each 

 air-chamber, vessels necessary to maintain the vitality of the interior 

 of the shell, and of the transverse septa. The mode of ascent and 

 descent ascribed to the Nautilus Pompilius is inapplicable to such 

 animals, and their movements are probably effected by muscular 

 exertion only. 



P. 310, 1. 20. Mr. Murchison in his excellent memoir on a 

 fossil Fox found in the Tertiary Fresh-water Formation at (Enin- 

 gen, near Constance, gives a list of many genera of fossil Insects 

 as well as of Crustacea, Fishes, Reptiles, Birds, and Mammalia, 

 discovered in the slaty marl and limestone of these very interest- 

 ing Quarries. See Geol. Trans. Lond. N. S. V. III. p. 277. 



P. 310, Note. The collection of fossil Insects from Aix de- 

 scribed in the paper here referred to, was made by Mr. Lyell in 

 conjunction with Mr. Murchison. In the same paper is noticed 

 the preservation of the pubescence on the head of one of the 

 Diptera. See Ed. New Phil. Journ. Oct. 1829, P. 294, PI. 6, 

 Fig. 12. 



P. 336. In the concluding note of my first edition, I men- 

 tioned Ehrenberg's discoveries of the silicified remains of fossil 

 Infusoria in the Tripoli, or polishing slate, (Polierschiefer Werner,) 

 from Bilin in Bohemia, and from four other localities, and also his 

 discovery of similar remains in the slimy Iron Ore of certain 

 marshes. I am now enabled to extract farther information from 

 his memoirs upon this subject, presented to the Royal Academy of 

 Berlin, in June and July 1836, and translated in Taylor's Scien- 

 tific Memoirs, February, 1837. 



It is stated in this memoir, that the mineral springs of Carisbad 



