Formation of Flints in Chalk. 415 



tracted, terminating in a root or peduncle abruptly truncated, thick 

 and solid on one side of the central tube, but usually open on the 

 other, to allow the passage of water to the interior (see PI. 24, No. 2.) 

 This peduncle bears marks of separation by violence from the point 

 of attachment on which it grew, and which seems not to have been 

 the chalk in which it is now imbedded : the lower portion of the 

 peduncle from which it was torn off has, I believe, been never yet 

 discovered. 



The position of the Paramoudra? in their matrix is irregular ; 

 (see PI. 24. No. 1.) sometimes they lie horizontally, at other times 

 are inclined or erect ; they are generally insulated, and altogether 

 unconnected with the thin stratra of siliceous nodules which occur 

 in the same chalk pit with them. They often lie across these strata 

 without producing any effect on them, or being themselves affected 

 by them. Sometimes the extremities of two specimens are found 

 in contact ; but this seems to be the result of accidental juxtaposi- 

 tion, not of any original connexion of the animal bodies.* 



The animal history of these fossils is involved in much obscurity, 

 as they display no traces of internal organization sufficient to de- 

 velope the habits and character of the original bodies, whose ex- 

 ternal features are so distinctly preserved. The central aperture 

 or pipe was calculated to allow water to have access to the interior 

 of the animal, as is the case in many hollow spunges, that have 

 large single tubes passing into their center, and usually closed at 



* I mention this because an idea used to prevail at Belfast that they are occasionally 

 found linked together in a kind of chain. For my acquaintance with this fact and many 

 others relating to the history of the Paramoudra, 1 beg to acknowledge my obligations 

 to my kind friend Dr. M'Donnel of Belfast, to whose ardent love of science, and ex. 

 extensive knowledge of the natural history of the north of Ireland, I am indebted for 

 much valuable information on the Geology of that district. 



3 g 2 



