304 TUBE IN THE PARAMOUDRA. 



ginal connexion of the animal bodies." * Geol. Trans.,' vol. iv. 



The superior terminal Paramoudra, I have always found 

 round and closed at the top, but upon breaking it, there will 

 be found in every specimen, the tube passing through from 

 the chalk into the substance of the flint, and coming out on 

 one side two or three inches below the top. 



Mr. Lyell, in his paper read at the meeting of the British 

 Association, 1838, says that each Paramoudra contains inva- 

 7'iably the cylindrical nucleus of chalk : this is not always the 

 case, for during one of my visits to the pit at Horstead last 

 October, I was breaking a specimen for examination, when, 

 instead of finding chalk, I found it flint throughout, and the 

 hollow tube quite silicified passing through the centre, as I 

 have invariably found it passing through the chalk nucleus. 

 I have since found another similar specimen at Whittingham. 

 I have observed in the chalk nucleus, several Ventriculites, 

 Ananchytes, Plagiostoma spinosa, Terehratula octoplicata, 

 and indeed, most of the fossils common in our chalk ; and in 

 almost all the specimens that I have broken, have found mass- 

 es of Pyrites usually attached to the flint, but projecting 

 into the chalk nucleus ; occasionally I have observed the 

 belemnite passing through the flint, and entering the chalk 

 nucleus. 



Norwich, Feb. 10, 1840. 



[Can this curious tube be in any way connected with the aggregation 

 of flinty matter forming the paramoudral column ? If the pot stones 

 were originally sponges, or organic bodies of any kind, how comes it that 

 when broken they display no structure, or at any rate, nothing which will 

 distinguish them from the ordinary nodula or tabular chalk-ilints ? 



After spending a morning in the chalk-pit at Horstead, near Norwich, 

 and breaking a considerable number of the Paramoudras, we found the 

 tube present in every instance ; sometimes however, so nearly obli- 

 terated as to be only traceable by the discoloration of the chalk around 

 its original site. The tube varies in diameter from the thickness of an 

 ordinary-sized quill, to that of the finger. The wall of the tube is gene- 

 rally of a green colour, and about as thick as the rind of an apple ; the 

 cavity is filled with chalk. Mr. Bowerbank finds it to consist of siliceous 

 particles. The mode in which the tube quits the chalk, and passes through 

 the flint cap of the terminal Paramoudra is very remarkable. We believe 

 the sole merit of this discovery to rest with our correspondent Mr. Robt, 

 Fitch.]— Ed. 



