ANNALS OF NATURAL HISTORY. 



XVIII. — On the Organic Origin of the Potstones or Paramou- 

 dras of Whitlingham, near Norwich. By Prof. Ehrenberg 

 of Berlin. 



At the late Meeting of the British Association in Newcastle, 

 Mr. Lyell made a very interesting communication on the verti- 

 cal funnel-shaped flint tubes, three feet in length and one in 

 width, which are filled with chalk, and traverse the horizontal 

 layers of chalk near Norwich and in Irelahd. Mr. Lyell inti- 

 mated that these flint tubes, known by the local name of Pot- 

 stones or Paramoudras, would probably be found to consist of 

 microscopic organized beings, similar to those which had been 

 discovered in other chalk flints. Prof. Sedgwick was rather 

 of opinion that they had the appearance of being merely petri- 

 fied fungi, since they quite resembled some forms of large living 

 sponges. Dr. Buckland, who had formerly considered them 

 of organic origin*, at present abandoned this opinion, and 

 viewed them rather as a product of the chemical separation 

 of the siHca from its mixture with the chalk, supporting him- 

 self by direct experiments which had exhibited similar phaeno- 

 mena. 



This difference of opinion among geologists of such emi- 

 nence and so universally esteemed, induced me to submit these 

 stones to a direct microscopic examination. During my stay 

 in London in September I obtained from the museum of the 

 Geological Society some small fragments of two of these Pa- 

 ramoudras, which have exactly the form of large specimens of 

 Spongia Infundibulum. The microscopic examination deter- 

 mined the organic nature of these masses. I failed to discover 

 in the interior of the stone the structure of well-preserved 

 sponges, which the exterior forms represented, and perceived 

 only contorted remains of decomposed vegetables (probably in- 



* See Trans, of Geol, Soc. First Series, vol. iv. p. 413. where figures of 

 them are given. — Edit. 



Ann. Nat, Hist. Vol. 2. No. 9. Nov. 1838. m 



